This was our first couple of beds. They were double dug, and framed with found wood and bought fir. Found wood is ideal. I have used a mixture of pine, fir, found wood, and rounds of a tree that fell through our fence. The rounds are actually my favorite, it gives the beds a very natural look. I sifted the beds to remove the Bermuda grass, rocks, and random pieces of glass and children's toys. Bagged compost was added, as we had not been there long enough to make our own (though as you can see in the background I also added a three bin system for composting). The the paths that surround the beds are about 6 inches deep and filled with wood chips to keep the Bermuda from creeping right back into the beds. Wood chips can be free, an aborist will be happy to give them to you as they will have to pay to dispose of them otherwise. The paths also work as a long term composting system. The bottoms of the paths are now a fine, black compost in this area. Probably this fall I will clean them out and add the compost to the beds. The wood chips also hold moisture. This was our first crop, mostly tomatoes and squash.