a big factor in reducing swirling is what towels you use to wash your car and what towels are used to dry it.
I have completely stopped drying with any towel that has split threading(this means no more microfiber on paint, interior only). From now on its Only tufted loop ends like on my Sonus waffle weave towels and the Councourse Buffing towel sold by Autopia car care.
As far as washing I don't use any of those washing mits found in most auto stores. I was using a Chenille sponge but I found that even after a couple of machine washes I can still find small traces of debris. If its good at trapping the dirt its also good at holding it. This may sound nuts but I wouldn't use one of those $3 sponges more than once. I've been using some neutral colored waffle weave towel for washing and never touch the dirty paint unless its first been lubricated with soapy water.
This basically means never going to any kind of public drive thru car wash. You shouldn't be going there anyways as soap should never see your soft top. The towels at public car washes are usually terry cloth wich will swirl your paint no matter how soft. its not the thread but the actual threading process that make terry cloth swirl paint. The wash mits used are also usually filthy from the previous car and I wouldn't wash my bicycle with those towels.
When washing you should be using two buckets. Once the soapy towel has made the first pass (down and away, NEVER sideways,back and forth) it should go directly into the second bucket of clean water. Similarly waxes should never be applied or removed in the Karate kid wax on wax off method. I think Mr. Miyagi's paints were much tougher than these soft German paints whcih are illegal here in America.
The washing mit and drying cloth can probably account for nearly all of the swriling on your paint. The other big part is buffing with a towel that should only be used to remove polishes and waxes. Use a dedicated Councours towel for final buffing and use speed and never pressure.
p.s. those of you with open wheels I picked this up recently and its the exact length for cleaning the barrel of the Carrera 5 spoke wheel. $6 at PepBoys
this is another great product for washing, one for each bucket.
http://www.autobarn.net/rodi/gritguard.html