I have not built my own, but one of our local ranges has a number of sweet barricades to shoot from. Go youtube "precision rifle competition" and you can get some great ideas.
The focus of barricades is how to "game" them, which will help you to overcome the handicaps inherent in their structures. That is why you see many folks running around matches with bags the size of pillows dangling from their belts. Those things are great when you need to shoot off of xyz barricade without a bipod. This is just one example of many...
Also, make sure to practice a lot of off hand shooting. Standing, kneeling, sitting cross-legged, and even going prone without the aid of any external supports (holding the rifle up off the ground, no bipods, bags, etc...) If you're not proficient with the many applications of a quality sling , and how much stability they can add to your positioning, you should definitely research them as well.
Best of luck!