I agree with Alex, do covers. Don't start it by "Hey let's make up a song". You need to know that you're all on the same page first.
Do any of you guys play more than one instrument? If so, switching instruments every now and then would be a good idea.
You need to know how other instruments work. It's helpful to have a basic understanding of guitar, drums, bass etc. A great musician is talented
musically, not just skilled in one particular instrument.
There are a lot of egos in a band. And there's always this guy that never shows up for band practice. At that point, someone has to take up the leader position and tell him that he has to change if the band is gonna get serious.
Sounds gay but videotape or record your stuff. Even your first jams. It's fun listening to how horrible you are as a band.
Having a band name, logo or a gimmick should be the least of your concerns, lol.
Few band members > A lot of them
Please for God's sake tune your guitars
before band practice and not during.
If your vocalist tries to do any of those metalcore screamo noises, stop everything immediately and seriously consider kicking him out. Vocalists tend to do that when they can't sing or do a real growl.
Buy a microphone, or make sure the vocalist has one. You can't hear him beneath all that music. In the words of Lemmy, "Only way to feel the noise is when it's good and loud".
Make sure it is loud.
I don't think a starter band should rent a rehearsal space. The best place to jam would be the drummer's place, if the neighbors don't mind. Which they will, because neighbors are assholes.