What modeling advice are you wanting specifically?
I read something about poke throughs so I'll comment on that.

You need to be aware of the areas that are going to give you poke throughs while you are modeling, so you either adjust while modeling or apply a modifier/tool/etc that will expand your model to a safe distance from the figure...or go around and adjust by hand.
I would also grab the loop around the knee, turn on a soft selection and slightly contract those loops so the legs aren't perfectly straight.

Modeling is a learning curve. You want to know ahead of time where your trouble areas are, unfortunately you won't know that until you start modeling and making things, converting them into figures and trying them out.
Phil tool works, or just break your model up in your app and name correcrtly (lShin, rThigh, etc).
Every 3d app is different but they basically all do the same thing. You really need to explore your tools/modifiers/etc to know what each little crazy thing does to alter areas that are troublesome. It might be well worth your time to purchase a tutorial on your program and watch a pro as he/she works, this is where you will start to pick up on the small details.
You'll want to start adding extra loops around joint areas (knees, elbow,etc) to help with bending too, like you did in the groin area.

Looks great and keep up the good work.

Comitted to excellence through art.