Once the base coat has dried, you will apply the main color with a dry brush. I used a nasty old brush that was hard as a rock. It doesn't really matter as long as it will put paint on unevenly. So if you are using a nice brush make sure to only put small amounts of paint on and even brush it back and forth on a paper towel to get off any excess paint. Then, start applying the paint until you have enough of the base coat peeking through to go for the style you want. I usually add some brown paint to my main color, but don't mix it in (see the above picture) so that the paint looks aged. I also use my finger to swipe paint unevenly on the sides. After I'm satisfied with the coverage, I like to add some definition to the edges and indentations on the frame by adding some brown paint mixed with a glaze medium.
I use the glaze medium so that the paint is thinner and takes longer to dry. I sand off a little of the top layer of paint to reveal the base color. I sand almost down to the wood on the edges of the frame. Then I apply the brown/glaze/paint with a q-tip. I work quickly and wipe away excess with a paper towel. You want the glaze to sit long enough to get into the cracks and set, but short enough to be able to wipe off the extra stuff that is outside of the cracks. Don't worry, it's easy and you'll get the hang of it. Once I'm done with this step, I stand back, look at it and decide if it needs anything else. I usually like to swipe some of the top color on with my finger (not mixed with any brown) randomly across the frame. And I'll usually take a piece of steel wool and sand off the edges here or there to let the base color show through. It's totally up to you how distressed you want it to look. And that's it! Let it dry, add you picture and hang it on your wall!