as mentioned, get warmed up, run around a bit, etc.
1. Be ready from the start. One of my early games there was a foul right after the tip. I didn't call it because you just aren't used to blowing the whistle that fast. And at the end if you are trail know if you have the shot at the buzzer. Again, first season. Luckily the shot missed because I was not ready to call it.
2. Had a new partner last season. He was involved in a play where an intentional foul should have been called and went up to me asking what should be done. If you have a play like that, learn when to make that call but there could be times when you can rightfully ask a question about what to do. If you know basketball you'll know when something is out of the ordinary like that and best to be on top of things and make the call yourself.
3. Not to get ripped here, but usually best not to call games too tight and never go into that "let them play" mode. That will vary of course but the best refs find some middle ground. Most people are fine to work. But if you don't like working with a few refs just get them off your list. Trust me it will make things easier but again something that probably should wait until at least a couple of games. A few refs are primary jerks. Meaning they get all offended if you call something in their area. Your job is to watch your areas. But you know what, sometimes calls are missed like a foul or a violation that your partner may not have seen. Again this is a balancing issue and most crews work well and learn to trust each other. they don't care if someone calls a foul in their primary because it could have been something they didn't see. Don't be afraid to step in at times. That starts becoming natural and most crews learn how to work with that and when not to make a call out of area.
Some coaches are just jerks. They will be nice to you before the games, then essentially try to tar and feather you. Bah humbug to them. That's just their Modus operandi. Talk to them, warn them, and just know when to give out the T if it is warranted. That reminds me, don't be overly concerned about 3 seconds, communicate with the players, hands off etc, but then be prepared to call fouls if it continues. There are minor fouls like that off-ball especially that can be avoided with communication but that only goes so far otherwise there can be freedom of movement restrictions. If you are trusting yourself, communicating when needed with the players, they will see that and I find things go smoother.
I always like having two whistles, extra laces and maybe a banana or something. You'll keep learning. And there will be some fun plays where you'll have no idea what to call. I remember some girls games where I was "wtf did I just see" I have no idea if that was even basketball. The good news is that well coached girls games can be the easiest ones to ref. One of my favorites game I ever did was a playoff game that went to OT, full crowd, and just a breeze to officiate. We could have reffed another game after no problem. It just varies. Try to stay on top of things, even games that are boring just work on things and stay interested/moving because assigners watch that.
I always like chatting a bit with the table. But also know that they could be parents of the players so keep that talk appropriate. Yes I may have given little Johnny jr a technical while Papa Bear was doing the books
Don't anticipate the foul. By that I mean, sometimes you'll think a foul is coming. I've seen refs blow the whistle on plays when it appeared that it was going to be a foul, but maybe at the last second the defender steps out of the way or makes a clean block. Ref calls a foul, and you know he's realized he's made a mistake. I'd rather a ref go with an inadvertent whistle but good luck with that
Learn the euro step, some refs get travel happy when a player just makes a fast move or one in the post. If you like reffing, then by all means stick with it. If not, it may not be for you and move on. I've known a few really good basketball players who just couldn't ref. They stopped which I credit them because there are others out there who keep at it when they should have passed that whistle on years ago.