From time to time I try to post (mainly for me) some useful information I have found online. So I found a good post on 2+2 poker forum. The post seems like a good summary of what I have been reading in order to improve my skills:
Just focus on refactoring and improving your code. Functions should do one thing. Classes should have one responsibility. Classes should have cohesion – most member functions should operate on most/all of the class variables. Otherwise you can usually split the class into smaller pieces. Functions and classes should be small. Try to limit the use of mutable data.
– muttiah on 2+2