Besides clay barring and waxing what can you do to keep a black or dark blue Camaro looking nice with minimal swirl and scratch marks?

Just a lot of work, don't use cleaner waxes, just carnuba and do layers, it'll make a difference. I had a Black '68 Years ago and it was work, work, work but it was awesome.

If you ever get a lot of scraches or swirl marks, wet sand the whole thing and then use a high speed wheel to polish it. You will need to machine wax it to get all the really FINE swirls out.

ORIGINAL: shnormo

If you ever get a lot of scraches or swirl marks, wet sand the whole thing and then use a high speed wheel to polish it. You will need to machine wax it to get all the really FINE swirls out.

Unless you really know what you are doing I do not suggest this. You can ruin a paint job in seconds with a high speed wheel, plus any wet sanding on an OEM paint job is very risky as the clear is very thin.
I suggest the clay bar as you mentioned but also look into the Porter Cable random orbit buffer, it will not burn the paint and is very user friendly. I am a big fan of 3M products, they make a compound (technicly it's a glaze) called Finessie It II Microfinishing Compound, I use that followed by their Swirl Remover For Dark Colors. When the car is clean it looks wet.
http://www.camaroforums.com/upfiles/892/asppg_In266338747.jpg

Beautiful SS JD1969.

There are a few tips, but mainly what is said above. Simple things makje a big difference though. Like when you wash your car, spray it off first, then wash from top down. Make sure you clean your spong after each panel to remove grit. A bra also helps if you are going to have to travel through construction areas or dirty roads (some people might make fun of you, but when you get there and take it off- no nicks, scratches- they will be jealous! Wax your car fairly often if your drive it often. I do it about 1 time for every 14-20 days driven. Thats about it. Have fun.Lots of work- GREAT results!

Don't bras trap dirt and debris, then in turn rub between the bra and car?

YES!!! Remember you can over wax your car. The pores can get stuck and clogged with wax. When we detail cars that have been waxed prior, we use a body shop prep to take all the old wax off. Try it next time you wax your car, I would bet that you can feel a difference. Claybar works wonders on making it smooth. I love doing it to black cars because it brings out a deeper shine.
http://detailyourcar.com/shop/overspray-clay-bars.php

I like the light cut bar. It is more agressive than the store bought ones so it yields better resuls. I like he Sterling Labratories wax enhancer as my lube. It doesn't evaporate as fast as the others. http://www.detailyourcar.com/shop/index.php?page=shop/flypage&product_id=317&category_id=e024465cc5f286d 0148e283ab8aac37d This can be diluted 10:1 so 1 gallon makes 10