If you want to drop and pick up you have to make sure you pick up color one from under color two, and color two over color one all the time. You are probably picking up one way most of the time no matter which color and that is twisting them.
My suggestion is that you keep practicing with two hands and probably practice more first with continental until you are more comfortable with it, unless you feel you are really comfy with it already. In the long run it will be worth your while and you will get faster and your tension will improve. If your floats are unsightly because they are too long, then you need to learn how to weave them in as you go, which also takes practice. When I first started color work I made a Kaffe Fassett Jacket (Jack's Back) and I was slow and awkward at first but by the end I was pretty good at it. The bad part was my tension changed during the project because I didn't practice the technique enough before hand and I ended up having to sew a seam (with a sewing machine) down one arm to make it fit because my tension got looser! It takes at least half a sweater's worth of practice to get your tension stabilized so if you have only done a small project then you need more practice to get it down.