Don't lay the cue across your shoulders and wrap your arms around it. When you're not shooting, hold the cue vertically. Don't turn the chalk upside down on the rails. It makes a mess and can even stain wood rails. If you smoke, don't bring your cigarette to the table.
Cigarettes sitting on rails leave burn marks.
Cigarettes in your mouth drop ashes onto the table. Not only does that make a mess, but a lit ash will burn the cloth. Don't bring drinks or food to the table. Food crumbs make a mess and spilled drinks can damage wood and cloth. Drinks on rails leave stains and could easily be knocked over onto the table bed.