Start basic, and just open a savings account at a bank or create a brokerage account at a major custodian (Charles Schwab, Fidelity, for example).

As a rule of thumb, you should have six months’ worth of living expenses in this account. Another good rule of thumb is to avoid touching this money at all costs, and never invest this money in risky assets like stocks.

It’s better to keep the money as liquid as possible, so even buying Certificates of Deposit (CDs) may not be the best idea. The purpose of this money is not to make you rich – this is your safety net.

How Should I Invest my First Thousand Dollars Saved?
How do I Calculate my Expenses?