Do not walk into the gym throw your stuff on a treadmill to reserve it, then disappear for 30 minutes.

Do not hang on equipment and/or weight benches you're not using while talking to someone for 30 minutes.

Do not sit on the bench while completely nekkid. The bench isn't clean, I don't think you are clean, and now I really don't want to even set my gym bag down on the bench on the outline of your bum.