Focus on Game Logic

The focus is what gives the game programmer his power.
It took me years to get to the point where I finally realized that most 2D games have a very simple set of code necessary from the graphics and collision ends. All you need is the ability to draw images and detect collisions, and maybe play sounds (qed eh), the rest is all game logic.

It binds the games together
The game logic is the truly unique and interesting pieces of code, had I known this long ago or listened to people when they told me to focus on making a game and not just the graphics and structural code, I would have had so much more experience programming game logic. Alas, it is what it is and I need to churn out game logic code like there's no tomorrow in order to catch-up on missed opportunities.

Use the focus Luke, let go your graphics!
So a word to the wise, frequently implement as many different types of game logic code as possible. This will help familiarize you with the implementation problems and challenges and help you flush out ideas much more quickly in the future. Believe me when I say I've spent enough time coding to realize the first time is always the hardest when implementing something you've never done. Each time afterwards becomes much easier, so much so that eventually you can implement it as fast you are able to type.

Not this crude matter!
By game logic, I am referring to things like scoring, inventory, turn based battles, tech trees, quest systems and puzzles etc... Also get into level design early, the hardcore performance heavy and resource intensive code doesn't matter as much as being a good content creator. Sadly these are things I never really got to implement, I was too busy focused on the structural OO design and making a complete engine package or more and more advanced graphics and 3D work. Recently I've been trying to undo years of focusing on the wrong thing. I was in the whole boat of the having a million small projects but none ever got finished.

You're my only hope
As many people will tell you one finished polished game is better than thousands of unfinished ones. This is due to the myriad things needed to polish off a game. Down to minute details that you don't anticipate like crouching and reloading at the same time. Things like balancing and making sure the game is fun and the shotgun isn't too powerful or too weak, the bfg is hard enough to get and you don't get it till later. All those things add up and sometimes are so specific to your game design that you would never think about it until you've implemented game X at least once.

Good Luck!

P.S. I'd love to hear of others experiences and advice when implementing game logic. And some good coding exercises to help refine your skills to make game making easier!