Filters
Some people filter their paint. Some never do. I have, but usually don't. If paint needs filtering, it's probably junk.
Anyway, the usual recommendation for filter material is panty hose. I've tried it, but it's messy and seems like it wastes a lot of expensive paint. I think I have found a better alternative.
My wife brought home a box of Lipton Black Pearl Tea. I noticed that, instead of the normal paper bag, it came in a pyramid shaped fine plastic mesh. I checked it out and found that it's not affected by lacquer thinner. With a pair of scissors, you can make two funnel shaped filters out of each bag. The beauty is that they are just rigid enough and the right size to fit in an airbrush cup, and they can be easily cleaned and re-used. So, if you filter paint, you might want to try them. The tea tastes OK too.