1. Pay off all credit card debt.
2. Have an emergency fund.
3. Get a job. Earn some money.
4. Invest at least 10% of your income.
5. Buy low-cost index funds. The easiest and best one-stop path to diversification is the Vanguard Total World Stock Index Fund for stocks. If you do not have access to it, then invest in a low-cost fund you have access to.
6. Determine the percentage of stocks and bonds you want to invest in.
7. Keep doing this forever.
Remember, investing is simple, not easy. The most difficult enemy is ourselves.