Lastly, I duplicated the whole image and pasted a new layer in case I screwed this next step up. . This new layer was blurred a small amount. Then using the history brush, I began bringing selected areas back into focus. Then I blurred the layer again, this time with about twice the blur. Again, I used the history brush to bring certain parts back into focus. This way, I get a controlled way to create a simple DOF effect and only effect the parts I want.
I hope you find this tutorial informative!
Christopher Tackett