There are several things you need to know if you want to be a good golf partner.
First, the golf course tends to be a quiet place. When people around you are teeing off or putting, try to keep talking to a minimum, and any other kind of noise to a minimum so you don't distract others. Along these same lines, turn off your cell phone or at least turn it on vibrate so that it doesn't ring at an inopportune time.
If your ball lands in the sand traps, after hitting, make sure to rake the sand so that the sand is level for the next unfortunate person who happens to find themself in the sand as well. It's bad enough to hit your ball into a sand trap, but it makes it far worse if the person before you has left a mess for you to try and play around. When you finish raking the sand, lay the rake to the side of the trap, out of the way for other golfers.
If you accidentally slice some of the grass when you take a shot (this is called making a divot) place the grass back on top of the shot it was torn from. If a divot is placed back onto the opening, it will only take about two weeks for the grass to heal, but if not, it could take as long as six months to fix itself.
Don't drive the golf carts onto the tee box or onto the green. This grass is the most sensitive and some courses fine you if you're caught.
Golf is still very much about manners. Not being considerate to golf course etiquette is far worse than taking a bad shot, so be courteous and remember these simple rules.