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/...

An alternative or supplement to books would be to do static code reviews with someone. They can give feedback that a book can't. For example, ask the reviewer what would make the reviewed code easier to understand.

Also, you could look up open source projects in the technology stack that you use and compare their code base to yours. In other words, follow a good example if it exists.

The Art of Readable Code is excellent.

http://www.amazon.com/Art-Readable-Code-Dustin-Boswell/dp/05...

I respectfully fully disagree with recommending The Art of Readable Code. Particularly, I take issue with the advice on comments, as well as the strange point that sometimes 'goto' is acceptable.

While there are some good sections on things like naming variables and "code aesthics" that kind of advice is not going to dramatically improve your code quality and I think most developers achieve better results with something like Clean Code or Code Complete.

I highly recommend Refactoring, by Martin Fowler.