Obvious, of course, but for some reason it doesn't seem to apply outside the actual shapeshifting magic. Then, the shapeshifters often behave like complete humans or complete animals, even when living in a society of their own.
1) Think about government. Think about it carefully. I think the best choice would be a mix between the two, or at least something more flexible than a strict human monarchy or a strict hierarchical system. If you think about it, a shapeshifter society is facing challenges that no other will, because it has to deal with people who are not confined to one body. That necessitates planning on the author's part for magic, but it also necessitates more careful social engineering.
How would a werewolf society- I know I ranted about people using werewolves only, but bear with me a moment- modeled strictly after a pack deal with someone turning back to human in the middle of a status fight? The changing werewolf might lose or he might win, depending on the situation, but what does his rank in the pack become after that? Has he used an unfair advantage, or disadvantage? Has he broken a rule by becoming human in such a situation, the same way that a low-ranker might by inching too close while the alphas eat? Does he have one rank while human, especially if he's bigger and stronger than most of the other werewolves, and one while he's lupine? Could someone be alpha who was a large wolf, but is less clever than the rest, and perhaps prone to being tricked by shapeshifters who are just as intelligent as normal humans?
You see how very quickly the situation becomes complicated, and that's a relatively simple example. With animals who have even more complex social structures, say bees in a hive, it can turn into a mess. Add in human complexities- for example, if the shapeshifters have designated mating seasons, is everyone compelled to mate, or would some of the leaders regulate it to make sure that unwilling females wouldn't be raped?- and it could upgrade to a Bloody Big Complication.
A shapeshifter society will have to have a government, whether that's by rank or a system of elders or gender or color or whatever, that takes into account their own people not being one thing all the time.
2) Show the relationship they have to both normal humans and normal animals. Unsurprisingly, maybe, most shapeshifters are often portrayed in relation to humans alone. These shapeshifters are usually gosh-golly-wow so much better, and have nobler ideals, lead simpler lives, are more in touch with the land, etc. (I don't think this is unique to shapeshifters, by the way; I think it's a manifestation of what seems to happen in any fantasy the moment a certain group of characters are portrayed as having longer lives, better magic, more involved gods, stronger destinies, etc. Somehow, they are now morally better, too. It happens with elves, Chosen heroes, persecuted religious and magical groups, and everyone else across the spectrum).
Do try to make it more complicated than that. Perhaps, just perhaps, the humans have good reason to hate or envy the shapeshifters. If the shapeshifters have warred on them in the past, or if they're the kind of animal that can eat humans, they certainly do. (I always wanted to see what would happen if a tribe of humans lived near a tribe of werejaguars, which are known among the great cats for being human-eaters). Possibly the humans have hunted and killed shapeshifters in the past in animal form, but for some reason other than the usual "mindless hatred" reason. Perhaps the shapeshifters are a prey animal. Perhaps they have valuable coats. (Hello, reversal of the werejaguar paradigm). It could easily be a war on both sides, or tense but peaceful on both sides, not just the humans hunting the persecuted shapeshifters.
As for normal animals...well, do the shapeshifters smell different? Look different? Behave differently? They probably would, and even if they look completely like a normal animal in beast form, they might easily send the truly normal animals into panic by changing back in front of them. Also, what happens if shapeshifters and "normal" ones of their kind are living in an area with limited food and competing for the same ecological niche? It might get nasty.
3) Consider structures. We'll take up werehorses this time. A stable would probably not be their first choice, especially when living in the wild. On the other hand, sleeping out in the grass and the dew could easily do damage to normal human skin, and if there are limits on the shapeshifting magic- which I think have to be there, or it really does become a deus ex machina- then they might not always have the option of changing back to horse to get away from the weather. On the third hand, build a normal human house, and shapeshifters in horse form will have problems with stairs and doors.
One possible compromise? Build a house-like structure, with a roof, and open sides so that the shifters in horse form can freely pass in and out. Ramps, instead of stairs, could lead from level to level. The inner rooms could be contained on several sides and sheltered from the weather, yet left open enough to insure the passage of an animal larger and taller than a human. There probably wouldn't be a lot of furniture or clutter, since sweeping tails and hooves, or possibly shifting itself, could knock it over. Instead of a bed, of either feathers or straw, there might be low cushions that would provide a comfortable sleeping place for a human and not get in the way of a horse.
All of this will depend on the species of shapeshifter that you choose, of course, and how often they change. I'm trying to imagine a true compromise here, since most books I've read about shapeshifters show them changing form fairly often, not, say, living exactly as a horse herd does and only changing back to human when they absolutely have to.
4) How does the food move around? If the shapeshifters are living exactly like animals, no problem (unless they're having to compete with similar animals, of course). Living exactly as a normal human village? Then we can probably assume they practice normal agriculture and the like, perhaps only changing into their animal forms for a bit of brisk flight or a run. But if they're compromising, or living separately from both humans and their animal phenotype because it's necessary...ah.
How do they eat?
It might be easy to say that these wereleopards slip into the forest every night and hunt down game, but again, it only works if each wereleopard has a separate territory- the case for natural leopards, except mothers with cubs- or if they're willing to wander. If they hunt only from a settled location, and they're numerous enough, the food would get depleted pretty quickly. Also, if they reproduce like normal humans instead of leopards, and take care of their children well enough that most survive (although see point 5), then the problem becomes even worse.
Why not have the wereleopards keep a somewhat tame herd of antelope or other prey, the way that kings used to keep a wood of deer? That way, they could know where the prey animals were fairly quickly, which might be essential when raising children; they could keep an eye on how the numbers were growing and how diminishing; and they could always let them out of whatever enclosure they were kept in, if they were fenced at all, when they wanted a chase.
For herbivores, compromise and have gardens. The gardens don't have to be grown just like human ones. Indeed, if the plants are different enough from ones that humans normally cultivate, they can't be. But, again, it would provide a more reliable food source, essential if the group of shapeshifters are going to live settled.
5) Consider the raising of children. Most animal family structures are radically different from the human one, and don't share the Western idea that two parents and children naturally belong together. Wolves raise their children, who may stay with the pack for a few years but then often strike out on their own. Remember, as long as they remain in the pack, the chances that they'll get to mate and have pups of their own are slim to none, given the alphas' control of their subordinates' fertility. Leopards are usually 'love 'em and leave 'em' in the sense that the mother mates, then rears the (usually one or two) cubs on her own, while the father wanders elsewhere. Red fox vixens are more likely to be rooted, with daughters not wandering far before establishing their earths, while the young dogs have to leave home to find territories and mates of their own.
If the family structure is a true compromise, and especially if shapeshifter children take as long to grow up as normal human children (probable, if their lives are human-normal or longer), then the mother wereleopard might well accept help from the father in raising the children. Again, though, it's not necessary. Perhaps in this wereleopard society, two expecting females will band together and raise their children in a two-mother family. Perhaps they will have several males around; they might be more casual about the concept of fatherhood. Perhaps they will live in the society with other shifters the rest of the time but retreat to the jungle or desert while the cubs are young, in order to prevent any danger of the older shifters killing them. This could depend on whether the shifters are born in human or animal form, too. Human form seems preferred, but again, there's no inherent reason for that.
I suppose this might be one reason that group animals like wolves are so popular to make shapeshifters out of. The writer doesn't have to wander quite as far from "normal" human families. Do consider it, though.
6) Consider how much social cohesion they have. This is a problem when you've got leopards, who are often solitary except if they're females raising cubs, and humans, who are often not alone unless they have no choice. A naturally solitary wereleopard is certainly a possibility, but so are naturally gregarious ones. How do they negotiate between the conflicting species instincts?
You could split it up by location. Perhaps they regularly hunt alone, but the settlement is considered anybody's space, and if a person wants to leave, they should just leave. Perhaps the society is open enough that anyone feeling the urge can just wander in and out as she pleases. Perhaps priority is granted to mothers with cubs, and so other wereleopards will be available for them, but the rest tend to form companionship based on individual choice (friendship could take on a whole new meaning when you don't have many siblings and weren't reared around a whole lot of children your own age).
The point, again, is not to split up the animal and the human. Shapeshifters are at heart both, or have the possibility to be. And, she added in a snobby voice, I think it's much more interesting when they're both, rather than humans with enhanced senses or animals with hands.
I think the next rant will be on handling disabled characters.