For a paint shop, cleanliness is next to Godliness. I regularly vacuum all the nooks and crannys, clean the airfilters, ( in and out). And wipe down the whole area, ( walls, floor, ceiling) with a wet rag to remove loose paint particles.
No sanding or bodywork in the paintbooth. If you have been doing either of those, you will need to either change out of dusty clothes or wear a coverall so you dont bring dust into the paint area. Make sure the paint area is as 'dusttight' as possible with only filtered air coming in. ( I use furnace filters covered with fine silk)
A few hours before painting, clean the paint area and let it settle,... a few minutes before painting, mist the entire inside very lightly with water ( mixed with a few drops of dishsoap) to trap all the dust thats left and get rid of static electricity. Let that settle a couple minutes, wipe the car down one more time with clean dry tack rags.