The simplest solution is restaurant work. I started as a busser making ~$100/day in tips, plus my hourly wage. After a couple years worked up to being a server making ~$200/day in tips. Couple more years and I am now bartending making ~$300/day in tips depending on where I'm working. This isn't factoring in my hourly wage. At my "best" job I was averaging 32 hours per week on 5 shifts at $16.50 wage, plus $315/day in tips. I made a fuckton of money that year and had ZERO degrees, ZERO certificates.

Yes, it really is that easy.