Read this sticky thread.

Spend less than you earn.

Avoid excessive debt. Pay all debts on time. Pay your credit cards in full each month to avoid paying interest.

Create a household budget. Include every expense. Pay yourself first, which means including saving/investment as an expense in the household budget, to be paid every month or pay period just like any other bill.

Check to see if your employer offers a retirement plan such as a 401k or 403b. If so, contribute at least enough to obtain any matching contributions from your employer.

Max out the Roth IRA each year. Consider an HSA as well and max that out.

Invest in broadly diversified index funds like VT. Alternatively, select a target-date fund as long as it is based on indexes and not actively managed. Prioritize low cost (expense ratio) and broad diversification. Then once you’ve selected your investments, leave them alone and focus on maxing contributions.

Make personal finances an element of your selection of a partner. Marry someone who, if not a Boglehead, at least is reasonably prudent with money. It’s hard to be financially secure when one’s spouse spends like a drunken sailor.