Still asking myself the same question.
1. Education. Depending on your age and time, it can be free.
2. Equipment. Do you have it? If you're still on p.1, Craigslist can give it to you for free.
3. Recording. This one's gonna cost you dear, and the less time/money spent on p.1-2, the more expensive p.3
4. Performing. It's usually free, or brings underwhelming income.