You need three things: planning, focus and productivity management.
For two first items, I guess there isn't so much to talk here, except two tips:
If you don't need really a computer to do anything, so don't use it;
If you don't need really go to Internet to do anything, so don't go there.
Yeah, I realize that Internet is our main enemy, when it comes to focus and productivity. :-(
Now about productivity management. Each person has his own productivity management method. I tried several and most of them have failed. I tried and liked Cube Anywhere, and it's simply fantastic to help you to manage activities, but at this moment I'm implementing a personal method, using:
A chronometer (an application called "Timer");
Two spreadsheets, taking note about my work time detailedly in one (printed) and summarizing in another (Google Docs) where I can see charts with my performance weekly.
If you can use Cube Anywhere, ou can learn how to use it in two or three hours and it'll be very useful.