Creating character packs

Hello everyone.  I've tried to find an answer to this question on the boards, but not had much luck.

If I wanted to create a character pack with approximately 25 basic poses and expressions, what would I need to do for it to be successful, and how long do you think it would take? I haven't tried this before, but would really love to start having a noticeable "our people" feel to the content we are creating.

We haven't got a lot of resources to throw at it, so rather than jump in with eyes shut and make a mess of it I thought I might ask first.  Thank you for any help you can give me.