Can't say I agree with Aero on this one: Mylar (alone) has always worked just fine for me.
Go to your local WMart (man, I hate to say that) or anywhere with an outdoors department, and find a "space" blanket (survival blanket?), it will give you a (roughly) 6 x 8 foot piece of aluminized mylar for a couple bucks. This will be enough to last for a good many streamers and chutes. No need at all (IMHO) to add ripstop (any color) to the backside.
Cut a strip 2-3 inches wide, 3-4-5-6 feet long, and you have a streamer.
For a rocket design like a Commanche (something that gets up there pretty high) you don't want to use a parachute, or a long streamer. You want it to come down fairly quickly, or you won't get it back at all. I would recommend you start with a short (2 or 3 foot) streamer to see how it performs for you, and if you need a longer one it is easy to change out. I think you will be amazed at how much visibility a silvered streamer adds to a descending rocket (even a short streamer).
You are right to start with single-stage launches, and work your way up to more stages. Don't forget you can use B booster motors, and you can rig an adapter for the bottom stage to use an A or B booster instead of a D motor. Hope you have a really large launch field..... (and I hope that sounds ominous enough). For such a design, you may want to consider leaving the fin trailing edges square (for strength) and soak the tips with some CA for reinforcement against bumps and scrapes during landing.
In my experience, rocket colors up in the air don't matter much. If it is low enough, and big enough, you will see it. If it is high and far away, no choice or amount of color is going to make much difference. It is far more important to be able to locate your rocket on the ground, post-flight. At that point you need some color that stands out from the ground (and whatever trash is scattered about). Even on the ground, a silver streamer can help, because if there is any wind at all the motion and reflection will help catch your eye. Other than that, choose the colors you like, or the colors you think are jazzy, or your kid's favorite color---it's mostly a matter of preference.