A million-pound Stocks and Shares ISA sounds like the sort of thing that happens to other people. It isn’t. But here are the tried and tested steps to help get there.

1. The best time was 20 years ago, the second best is today

The most powerful force in long-term investing isn’t stock picking — it’s time. Compound growth multiplies wealth. An investor who starts at 25 adding £500 a month will retire with roughly three times more than someone who starts at 35 with the same contribution. Same money. A decade’s head start.

2. Contribute regularly

When markets fall, your monthly contribution buys more shares. However, when they recover — and historically they always have — those cheaper shares deliver bigger returns. Investors should consider setting up a direct debit the day after payday. Make it automatic. Remove the temptation to pause.

3. Utilise the ISA limit, if possible

Every pound invested inside an ISA is sheltered from income tax and capital gains tax — forever. Unused allowance disappears at the end of each tax year and can never be reclaimed. At £1,000 a month, an 8% annualised return reaches £1m in around 28 years. Every extra contribution shortens that timeline.

4. Well-chosen stocks outperform cash

Cash ISAs are safe and reliably lag inflation. Equities are the only asset class with a strong long-term record of building serious wealth. What’s more, over half of my investments have at least doubled in value over the past three years. Celestica and AppLovin delivered 1,000%.

5. Reinvest every penny

Reinvested dividends compound alongside your capital. Over decades, they can account for more than half of total returns. Most brokers offer automatic reinvestment. Turn it on and leave it alone.

None of this requires genius or a large salary. Just patience, consistency, and a start.

Where to invest?

The above is great, but it’s largely theoretical. Investors need to know where to put their money, and this can be where many trip up.

Novice investors are typically guided to build some diversification. This could mean committing to buying a well-researched stock or two each month. Or a good starting point could be buying shares in a diversified asset like Scottish Mortgage Investment Trust (LSE:SMT).

The investment trust is managed by Baillie Gifford and holds stakes in dozens of companies spanning both public and private markets. Its portfolio is deliberately concentrated in high-conviction, long-term growth businesses — from established giants such as Nvidia and Amazon to unlisted innovators in biotech, space, and clean energy.

For new investors, this offers genuine global diversification through a single purchase. Rather than picking individual winners, buyers gain exposure to a curated basket of companies that Baillie Gifford believes can grow substantially over a decade or more.

That said, Scottish Mortgage isn’t a quiet, steady compounder. Its share price fell around 45% between late 2021 and 2022 as rising interest rates punished growth stocks hard — a reminder that its concentrated bets on early-stage and private companies can produce steep, swift drawdowns. It has since recovered meaningfully, but volatility comes with the territory.

Currently, it’s heavily exposed to SpaceX — that’s something I quite like. For investors comfortable with that risk profile, it’s well worth considering.