Thanks for the response, Andrew.
Do you have any tips at all on how to ensure that the edges are parallel? I tried sanding the edges as well, and they still didn't turn out that well.
I guess next time I will have to try and take the wood to a local woodworker and ask him to cut the miter joints for me?
Thanks for pointing out the possibility of pocket screws. Have you used them on miter cuts? For some reason, all the demos seem to be using them with butt joints instead of miter joints.