Some general rules to abide in the gym.
Demonstrate good form above all else.
To do otherwise is to make your training both inefficient and to increase your risk of injury. Not to mention, you will look foolish!
Put your weights away after use (even if they were already out).
There is no room for laziness at the gym. Others will create a mess, hold yourself to a higher standard.
No texting/emails/phone calls/social media during a workout.
You are there to train. During rest periods, focus on what you need to accomplish on the upcoming set.
Show good spacial awareness.
Others use the gym, be aware and considerate of them. There is nothing worse than someone getting in the way when you are in the middle of a set.
Clean up your sweat.
For obvious reasons!
If it works with your rest times, allow people to 'jump in' between sets.
Provided it doesn't deter from your training.
Use mirrors to look FOR yourself, not AT yourself.
Focus on performance over aesthetics.
If you provide someone with a spot, do not touch them or the weight unless it becomes a matter of safety.
Expect the same in return.
People will do things differently - it doesn't matter, just focus on yourself.
You cannot judge someone on their training as you likely don't know their goal.