There have been a couple of times where my team has shot me in the back, but it does happen. So, I recommend that you tell your team the basic area you will be located. Sometimes you may not be able to follow your own plan, therefore you should just take a chance. Anyway, your team should know or you should tell them not to shot anything they are unsure of. This will help prevent them from accidentally shooting you or other members of your team.
Gear is a very important of being a successful sniper.
You also need a good goggle system. You will spend a lot of time on the ground, and will most likely get hit in the facemask. You also want to keep it clean to make it easier to spot opposing players. Another item needed is a paintgun. A lot of snipers will use pumps because they are more accurate and have better range.