Make sure you're compatible with your bandmates. Compatible in your goals. Compatible with where you want to go, the size of the commitment you want to make. It's important that everyone is on the same page. Do you only want to play your songs and some covers? Are you opened to playing other bandmate's songs? Be opened from the get go about what you honestly want.
What bands do you all like? Where do you agree and disagree in your musical opinions? Is there enough overlap and do you seem to enjoy each other's company? Do you want to travel with a band or just stay in your local region? There's no use putting time and energy in a project if everybody has different ideas about what's going on. Passive agressiveness is the enemy. I know because I hate confrontation, and often in my life I've slowly but surely agreed to things that I would regret later. As soon as something doesn't feel right, have an opened discussion. Take notes of who says what, and if you can record the meetings with everyone's ok, all the better. So many times people don't remember what was said, etc.
We are all human and imperfect. We all come into situations with our own desires and motives. Often times these motives contradict. If there's two songwriters and they don't want to play each other's songs, figure it out early. Ask hard questions. If it isn't the right situation nip it in the but right away.
If you're at a show and something pisses you off, don't yell at your bandmate in front of everyone. If you have to communicate take him or her aside and quietly talk about the issue. Say you will talk about it later where there is privacy and you can have a more spirited discussion. Getting into fights on stage is the worst. Avoid it.
Try your best to have your electronic stuff under wraps. A few nights ago, I had a brand new amp and new cords and for some reason they weren't working. One of my mates got really pissed and thought the cord was broken but it wasn't. He threw a cord at me and told me to throw out the cords that don't work. But he yelled it at me. It was uncomfortable. When I tested out the cord that didn't work after the show, it worked. I wasn't sure why it wasn't working at the time and just needed a minute or two to figure it out.
Do the musicians you're playing with like everything to be exact compositions or do they like things to be more fluid and improvisational? A lot of times I try different stuff with my songs. I don't change it that much, just enough so it can still be followed. Some people like the unpredictability of that, and some people hate it. Make sure to really get to know the personalities you are playing with and what everyone prefers, and if you all have enough in common to make it work.