I like to wet sand with soapy (Dawn) water.
Then wipe it down with laquer thinner.
Then hit it with a tack cloth right before painting.
Don't touch your boat once you have started this process with your bare hands. I use vinyl gloves through the whole process.
All of my paint jobs have some dust in them somewhere, I don't have a professional paint booth.
To keep this to a minimum I clean my painting area.
Wipe down the walls and sweep the floor really well.
Once the dust has settled from the sweeping wet the floor down really well.
Any dust that happens to get stirred up will stick to the water on the floor if you are lucky enough to have it miss the ski on the way down.
Base coat/clear coat is great for hiding dust imperfections. During your first coat of clear you will see some specs that you missed, and some that you SWEAR were NOT there before you started clearcoating. Those are not the end of the world. Once your first coat of clear has cured long enough to sand you simply wet sand out the bumps with soapy water, wipe down with your degreaser and do a final wet coat. This time around most of the boat should be pretty smooth and assuming that you didn't paint it wearing your favorite Chistmas sweater with your girlfriend's persian cat under your arm, there should be minumal sanding. I use PPG's DC3000 clear, if I paint over my first coat within 3 days (I reclear the same day just because I am paranoid and the stuff sets up in 1 1/2 hours) it'll still have a chemical bond, meaning I don't have to sand down the whole ski for a mechanical bond which means I am not creating as much dust as I did the first time around and it's a quick and easy clean up.
If for some reason you have a horrible dust speck in your final wetcoat you can repeat the process, or wet sand it with some 2000 then cut and buff the paint using cutting/polishing compounds. I hate cutting and buffing, I love painting.
This is what I do and it works for me.