Just started to wrap my head around the whole retopo thing and have a few noobish question

Any help will be appreciated.
What are some general tips and theory behind retopologizing a highres model to a game-ready mesh?
What are differences between retoping clothing, organic and hard surface?
What needs to be retopo'ed together and what separate?
What to think about when doing retopo work etc?
Replies
Just a few tips :
- Look at the wires of lowpoly models made by more experienced artists
- Think in term of silhouette. If a poly doesn't affect the silhouette, remove it, it's useless.
- Check the wiki for organic retopo : http://wiki.polycount.com/CategoryTopology?highlight=%28\bCategoryCharacter\b%29
But as I've already said, the best way to learn that kind of stuff is to try and fail over and over.