Hey Brenda, show us a picture! A great way to pick your thread is to lay a couple strands of thread across the top, and see which one blends in (or stands out, whichever look you are going for) as desired.
I agree, going with one color will probably make you happier in the long run. I am no expert either. I recently quilted a multi-colored top (white sashing), and a pink bottom. I did white on the top and pink on the bottom, and there are bits of pink bobbin thread that poke through all over the top. Its not really that bad, but for your first attempt probably easiest not to fight the bobbin monster too!
Also, take a couple FQ and sandwich them with batting to make sure your tension is working before you start on your quilt. I usually test my tension on my test sandwich everytime I change my bobbin, just to make sure.