It seems like common sense, but not everyone is aware of 'gym etiquette'. Grab a clean towel and take it along as you move from one machine or piece of equipment to the next. Wipe down where you touched the equipment, even if you don't feel 'sweaty'. Gym equipment can be covered in bacteria from multiple people using it all day long. The kind thing to do is make sure you wipe it down with a towel, or better yet, an antibacterial wipe (many gyms offer these near the machines and weights). You'll feel better and so will the other folks around you!