Investing has a reputation as something you start "once you have real money" — as if there's a velvet rope and a minimum buy-in. There isn't. As of 2025, the big-name brokerages charge $0 commissions, require no account minimums, and sell fractional shares, meaning $100 — even $10 — buys you a working slice of the whole stock market. The hard part was never the money. It's knowing which buttons to press and which traps to walk past. This lesson is that map.
What a brokerage account actually is
A brokerage account is just an account that can hold investments instead of only cash. Think of it as a checking account's adventurous sibling: you transfer money in from your bank, and then — the step a bank account can't do — you use that money to buy stocks, bonds, ETFs, and funds (the building blocks from lesson 1).
The big established brokerages (think Fidelity, Schwab, Vanguard) are all, as of 2025: free to open, $0 commission on stock and ETF trades, no minimum balance, and protected by SIPC insurance (up to $500,000 if the brokerage itself fails — it doesn't protect against your investments going down, nothing does). For a beginner, the differences between them are minor; opening one takes about 15 minutes and your Social Security number.
Taxable brokerage vs Roth IRA: pick your container first
Before you buy anything, choose the type of account — it determines how your gains are taxed:
- A standard (taxable) brokerage account has no rules: deposit any amount, withdraw anytime. The cost: you owe taxes on dividends each year and on profits when you sell.
- A Roth IRA is a brokerage account in a tax-proof wrapper for retirement. You fund it with money you've already paid taxes on, and then — this is the magic — all growth and withdrawals in retirement are 100% tax-free. The catch: you need earned income (a job) to contribute, there's an annual cap (around $7,000 as of 2025), and the earnings are meant to stay put until age 59½. Your contributions, though, can be withdrawn anytime without penalty — which makes it less of a lockbox than people fear.
The common rule of thumb for beginners with a paycheck: Roth IRA first (after grabbing any 401(k) employer match, which is free money). Decades of tax-free compounding is the best deal in the tax code for young people in low tax brackets — the full reasoning is in Roth vs traditional. Use a taxable account for long-term money beyond the Roth cap, or for goals that can't wait until retirement.
Expense ratios: the one fee that actually matters
Every fund charges an annual fee called the expense ratio, skimmed invisibly from the fund's value. It looks laughably small — 0.03% is $3 a year per $10,000 invested; 1% is $100 a year. Who cares about $97?
You do. Because the fee isn't just money gone — it's money that stops compounding, forever.
Dollar-cost averaging: the anxiety cure
"But what if I buy right before a crash?" Meet dollar-cost averaging (DCA): investing a fixed amount on a fixed schedule — say $25 every week — regardless of what the market is doing. When prices are high, your $25 buys fewer shares; when prices crash, the same $25 automatically buys more. You never have to decide whether now is a good time, which means you never freeze.
$25/week is $1,300 a year, about $108 a month. At a 7% average return, that's roughly $18,700 after 10 years (on $13,000 of deposits) — and about $284,000 after 40 years on $52,000 of deposits. From coffee money. The compound interest calculator will run your own numbers, and the compounding lesson explains why the 40-year figure looks impossible but isn't.
The first $100, step by step
- Pick a big-name brokerage (Fidelity, Schwab, and Vanguard are the usual suspects). If you have earned income, open a Roth IRA; otherwise a standard brokerage account.
- Link your bank and transfer $100. It typically takes 1–3 business days to settle.
- Buy a broad, low-cost index fund or ETF — an S&P 500 or total U.S. market fund with an expense ratio under 0.10%. Thanks to fractional shares, you can invest the whole $100 even if one share costs $500.
- Automate it. Set a recurring transfer-and-invest — $25/week, $50/month, whatever survives your budget. Automation is the entire strategy; willpower is not required and shouldn't be trusted.
- Ignore the news. Your account will drop sometimes — lesson 2 covered why that's the price of admission, not a malfunction. Check quarterly at most. Boredom is what success feels like.
What to walk past
The same app that sells you an index fund will dangle shinier things. Skip, for now and probably forever:
- Single "hot" stocks. One company can go to zero; your index fund already owns the winners — including the next one nobody's picked yet.
- Crypto FOMO. Wildly volatile, no underlying earnings or interest paying you to hold it. If you must scratch the itch, cap it at money you'd cheerfully set on fire — after your boring fund is automated.
- Day trading. Studies of day traders consistently find the overwhelming majority lose money versus simply holding an index fund. The people who profit from your trades are the platforms.
- Anyone charging a percentage of your money to manage it at this stage. You just saw what 1% does over 30 years. A three-step plan — index fund, automate, ignore — doesn't need a salaried driver.