You've got the right idea. Putting the different forms on different bars is the best way I've found. Especially because I use 1-5 for my main attacks, it only makes sense to have it that way. Remember, if you press Shift+number you can switch between bars pretty easily. Make sure you have the same buttons on each bar for different forms (I have bird on 0, wolf on 9 and ape on
so that no matter what bar you are using you can switch without even thinking. Same goes with your pots.
Also considering putting your healing skills on Alt+1-3. That way you can quickly change to human and throw on a heal really quick. As Alt is already practically under your left thumb this is really easy. I find that really helpful against bosses. I'm usually in wolf, so I just build up a few charges, switch to human, cast the party heal and switch back.
I don't like the ctrl bar because it is not as easy as the alt bar to use. It is, however, good for some things. I put my mount, weapons, puppet skill and other such things here. I also put my put my bird speed buffs there in case I need a quick getaway.
My way probably isn't the best but it's been working for me so far.