in no particular order.
Merch. Even if/when You sign a deal, don't give up the rights to Your own merch. It was "unheard of" when I first presented the idea when haggling such deal years ago, but labels have understood the reasons, and come up with compromises.
Don't be afraid of playing small gigs (regard all gigs as workdays and when it fells tiresome comparehow many workdays a year You used to do).
Try to stay away from family life and too demanding weird relationsips with needy people or anybody with attention issues. It's not necessary but it helps things a lot if You plan to not be at home by sunrise on more than one day weekly. At least think twice about GF/BF candidates without precious relationship with musicians, just how much shit are You about to take for being late from a date because You were at rehearsals - at work! Playing in a band members can be like being married to three or four other persons with busy schedules, always checking calendars and yelling each other about shit they missed.
(Addendum to precvious: buy eveybody one and make sure EVERYBODY uses their calendar. Build up an aura where rehearsals are regarded as important as public appearances and practice like hell. Try to sell the idea tto the band that it isn't good work ethics to skip even practices for pleasure. "What You mean You have birthday? Awesome, we have CD, birthday beer and a donut waiting for You, come play the rehearsals and THEN, in tow or three hourts, go back to to party with YOur family/GF/friends." Same with hang overs. Don't tolerate any of that shit to ruin schedules for others because of that, and show a good example Yourself. (that sure was hard at times but a few rough noon rehersals teach the lesson)
Also have a cover project/ party band or such that makes a little money to make up for the time offs when the rest of te band is unable to play shows for reason A, B, or C. If You have too many projects, that will blur Your focus and distract You (I had seven projects once, of which three were actually active) BUT it can also spread a word about Your main band through the other bands' members, their friends, and fans. Also, play the second set of Your own party/ classic rock/ country 'n'western/ polka songs, sell Your album at gigs.
AND try to sell Your cover band shows to big organizations, because if they're really big and just asked U2, they've probably got smaller staff events too taht You'd fit in better. Consider also spicing the show up with other performing arts. Find a good stand up comedian, dancers, mud wrestlers or shit and try working together. That shit gets noticed and get You asked to come again in the more wet company parties.
Offer to work as the soundguy at clubs You frequent, ask their soundguy straight up when he is having vacation and does he need somebody to back him up. Learn the trade from him and ask at Your own shows about everything worth knowing from the soundguys. Some turn out really talkative whne anybody cares to ask them. Same when You visit studios. Then read books, and ask people at Your gear shop.
Or work as a stage hand. Yeah, it's HARD work, but if You prove Yourself to be a good, trustworthy guy that learns quick, is always and without exception in time, turns up never drunk at work or even having bad hangover and does what ever show... You're in. Find a company /venue that doesn't rip You off, try to find better deals or work for a few, and if You actually enjoy it, consider specialising in something that not everybody does (like being a climbing rigger, a steel hand, operating the lights, being a trustworthy geet tech, or become the guy in teh crew that knows always somebody the band can rent their weird gear from).
Also, if You're good with people and explaining, try finding a few students and give lessons. Haven't done much that myself but Is there perhaps something that You know well and can teach from experience better than others? Concentrait on that and You might dodge going through the elementary basics and having to tune Your students' geets
I used to make a living for myself for a few years, before I had to start taking care of other people and I found a steady day job also.