How do I start investing with no money?

Start with $1. Micro-investing apps and fractional shares removed the barrier. Priority: 1) Emergency fund (1 month expenses), 2) Employer 401k match (free money), 3) Roth IRA ($7,000/year limit), 4) Total market index fund (VTI, VTSAX). $100/month at 7% for 30 years = $122K.