The Art of Readable Code is excellent.
http://www.amazon.com/Art-Readable-Code-Dustin-Boswell/dp/05...
http://www.amazon.com/Art-Readable-Code-Dustin-Boswell/dp/05...
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.