A great article wrote by a game designer working here at Ubisoft.

It's a great list of basic physic problem you might encounter and how to solve them when prototyping (or even working on a final product), a gameplay. It apply well on 2D platformers but I'm pretty confident that those insights can be usefull for 3D games too, and not only platformers.

I let you with Yoann as he did a really great job.