With a few exceptions, I use two frame styles in 5 colors to frame pictures up to 22x28 in size. They are all wood frames with wide borders. I find that these frames work well on most of my work. I match a picture with the frame that I think works best with it in isolation, but my pictures will work well in most of these frames (depending on the context in which you will be displaying them).
Below are pictures of my 5 main frame styles. These are photographs of my 18x24 prints, smaller prints will have frames that are proportionally wider and my extra-large prints will have frames that are proportionally narrower since the frame width is the same in all sizes. I mat these size prints in 4 ply white museum-quality mats. If you have additional questions about frames, feel free to contact me.