We've established what's important, haven't we? First off, you need to find a style you enjoy playing. This will make it easier to continue to step two: Composing. THOROUGHLY composing. Compose until your brain hurts, then compose some more!
I wrote thirty to forty songs in the beginning, and only twelve of them made it to my band's debut album. Nothing but a couple of riffs from the original twenty made it, either. Don't be afraid to lose your beginning songs. It's highly unlikely that everything you start with will be good enough in the end, and that's fine.
Now, once you've got your music all written up, the road forks a bit. There are many different approaches, and of course, I'm one man. I haven't taken all of the approaches possible. So I can only speak to my own experience. But it'll be useful, I promise.
Record labels, contrary to popular belief, DON'T WANT TO HOLD YOUR HAND. They want you to stand on your own two feet. The more you can do without them, the more attractive you look to them. Think about it: Music business is STRESSFUL.
Labels have a very tight budget. And they're terrified. They don't know how to deal with a world changed by the internet, and it seriously freaks them out. For the first time since labels existed, you can get music en masse without them. And that scares them.
What, you may ask, is my evidence that they're so scared? Well, people who are afraid tend to fall back on old habits. See, back in the '50s, rock and roll was just arriving on the scene, and it threatened and terrified the major players in the traditional music scene. People couldn't figure out where rock's popularity was coming from.
Turns out, independent labels, early peddlers of rock music, were bribing DJ's to play their music on the radio. When officials in the music business caught wind of this, they reacted in a manner quite similar to the way labels act today: They sued the hell out of everything that moved. They were anxious, they were tense, and they were unhappy. Just as they are today.
Now, let's answer the big question: How is this history lesson relevant? Simple. Because labels are so stressed over the sinking ship of the conventional music industry, you want to do everything you can to EASE their stress.
Labels don't want to have to shell out precious cash, delve into their tight budget, only to have their newly-signed band screw around in the studio like drunken morons during time you SHOULD be using to create your debut! Labels don't want to have to pay a producer to babysit your band and make sure you play your parts right! Labels don't want to build your fanbase for you! Hell, if they can help it, labels don't even want to have to pay an engineer to mix and master your album for you!
The more you can do yourself, the less the label has to do. The less the label has to do, the more willing they are to sign you. Why? Low risk, high reward. The less money they invest in you, the less sales they need in order to make a profit. You want to be a professional musician? The first step is ACTING PROFESSIONAL.
Take, for instance, Dream Theater. I know, I know: Drama. But hey, they did a lot of things right! John Petrucci and Mike Portney produced their albums, watching for each and every hint of sloppiness and saying, "Nope. Do it again," whenever they found it.
Alright, this is getting long. I've proven my point I think. I'll collect my thoughts and come back next time with a slightly more precise topic. Probably something more practical, pertaining to the steps you can take to look more attractive to potential promoters.
Until then, keep composing!