Posting late, but here's my experience with swirls, especially with black.
They're inevitable. Its gunna happen. However....
You can do a lot to keep them to a minimum until your yearly detail done by a pro. Its what I do with my Mustang (black).
I drove myself to the borderline of insanity buying 50 microfibers of everything. Polishes and waxes that promised to remove swirl marks and washes that promised against causing them. Ultimately, the only way to not get them, is by not touching the paint as much as you possibly can.
So, when washing, keep doing the 2 bucket method and when washing and drying, go in straight lines back and forth (no circles, no swirls!) and keep those microfibers clean! Then, when its time head to a pro. And repeat. Way I look at it is buying washing my cars myself, I'm saving a lot of money and use that money to pay for the details. Getting close to a year with my FiST (orange) and I'm starting to see some swirls. Detail time soon.