The first step is to be aware that you aren't writing succinct, manageable code - so you are already making progress :)

I'd recommend these books, mixed with some searching around for best practices for whatever specific framework/language/toolkit you are writing code with.

Clean Code

http://www.amazon.com/Clean-Code-Handbook-Software-Craftsman...

Refactoring to Patterns

http://www.amazon.com/Refactoring-Patterns-Joshua-Kerievsky/...