I agree with what Brian says. GTD isn't something that you pick up right away. I remembering being overzealous and trying to do all the steps at one time only to fall off the wagon.
Adopting the GTD system takes time. I took my cues from Zen To Done:
http://zenhabits.net/zen-to-done-ztd...tivity-system/
This version of GTD argues that you should get efficient at one part of the GTD system and then go to the next step.
For me, OmniFocus/GTD finally clicked in when I started doing the weekly review. During the weekly review, I prune my OmniFocus projects. Look for projects that can be deleted because they have been de-prioritized (either the time has passed that it is no longer relevant or I finally realized that this project is no longer important to me).
It's hard to trust your project/task list if you don't review it. By reviewing it every week, you'll be confident that your projects and tasks are still relevant today and there is no clutter in your life. Be vicious and go through your projects.
I tend to set new projects automatically to "On Hold" status in my Someday/Maybe folder. I already have enough active projects to keep me busy. During the weekly review, I'll go through my active projects and see which ones can be put back into Someday/Maybe. Then I'll look at my On Hold projects to see which ones I want to activate.
By placing many of my projects on hold (Someday/Maybe), I don't have to worry about seeing those project/tasks in my context view.
HTH