I am listing some of the animation tips I got on web recently, but some of them are old ones.......
I found them to be very useful...here we go
Jeff Lew's tip:
Happened to see the sneak peek of Jeff Lew's 3d character animation DVD. He advises not to have a bone joint in the chest area, and reasons it out very well. The rib cage is stiff and does not bend itself. Having a joint there will allow for bending which will look unrealistic and too 'spliney'.
Stefan Henry's tips :
It was good to dig this one out. Its a very old one, but definitely stands true till now and will stay that way for ever. In his article in Gamasutra titled Anatomically correct character modeling , he discusses the placement of bone joints effectively that will help proper posing of characters and will animate correctly, all explained with clear images.
Jeremy Cantor's tips :
His article over at Zaayats.com discusses various pitfalls in cg animation and offers solutions to them. Good one !