Start with a written objective
An investment only makes sense in relation to a goal. Before choosing anything, write down what the money is for, when you need it, and what result would count as success.
- Name the goal and the date: "school fees in 2031", not "growth".
- Decide what you would do if the value fell 30% — before it does.
- Write down what would make you sell. Revisit the document, not your feelings, when markets move.
Watch out for: Buying investments first and inventing the objective afterwards. That is how portfolios end up as a collection of unrelated ideas.
Know your risk tolerance and your risk capacity
Tolerance is how much loss you can live with emotionally. Capacity is how much loss your finances can absorb. They are different, and a portfolio has to respect both.
- Judge tolerance by how you behaved in a past decline, not by how brave you feel today.
- Assess capacity from your income stability, reserves, debts, and how soon the money is needed.
- Take the lower of the two. The plan you can hold through a bad year beats the better plan you abandon.
Watch out for: Confidence measured during a rising market. Risk tolerance is only revealed when prices fall.
Match the investment to the time horizon
Time horizon is how long the money can stay invested. It is the single most useful filter for deciding what is appropriate.
- Money needed within a year or two generally belongs in cash or very short-dated instruments.
- Longer horizons can accommodate more volatility, because there is time to recover from a decline.
- Illiquid commitments should only be made with money you can genuinely leave alone for the full term.
Watch out for: Investing short-term money in long-term assets, then being forced to sell at the worst possible moment.
Diversify across genuinely different risks
Diversification spreads money across investments that do not all depend on the same thing going right. It reduces the damage any single mistake can do.
- Spread across asset types, sectors, geographies, and — for private markets — vintage years.
- Look through your holdings: five funds that all own the same large technology companies are one bet, not five.
- Accept that a diversified portfolio will always contain something that is currently disappointing.
Watch out for: False diversification, and the assumption that correlations stay put. In a severe crisis, many assets fall together.
Respect concentration risk
Concentration is the flip side of diversification: a large share of your wealth depending on one company, one sector, one property, or one manager.
- Add up your true exposure, including employer shares, options, and pension holdings.
- Set a maximum position size in advance and rebalance back toward it.
- Be especially careful when your job and your portfolio depend on the same industry.
Watch out for: Loyalty to a position that has done well. Past success does not reduce the damage a future failure would cause.
Plan your liquidity before you need it
Liquidity is how quickly and cheaply you can turn an investment into cash at a fair price. It is easy to ignore until the moment it matters most.
- Hold a cash reserve so you are never a forced seller.
- Map when each holding could realistically be sold, and at what cost.
- For funds with capital calls, keep liquid assets earmarked to meet them.
Watch out for: Assuming an asset that traded easily last year will trade easily during stress. Liquidity tends to disappear exactly when it is needed.
Let compounding do the work
Compounding is return earned on previous returns. Its effects are modest early and substantial later, which is why time invested matters more than perfect timing.
- Reinvest income unless you need it to spend.
- Contribute regularly rather than waiting for an ideal entry point.
- Protect the process: interruptions, withdrawals, and unnecessary costs all break the chain.
Watch out for: Compounding works against you too — on debt, on fees, and on repeated losses. A 50% loss requires a 100% gain to recover.
Measure results after inflation
Inflation reduces what your money can buy. A return that looks positive can still leave you worse off in real terms.
- Judge outcomes in purchasing power, not just in currency amounts.
- Recognise that large cash holdings are safe from market falls but exposed to inflation.
- Consider how each holding might behave in a higher-inflation environment.
Watch out for: Feeling safe because the balance never drops, while quietly losing ground every year.
Control fees and costs
Fees are one of the few things in investing you can know in advance. They come out of your return every year, whether performance is good or bad.
- Add up everything: management fees, fund expenses, performance shares, platform charges, spreads, and taxes.
- Compare the total cost of two options that offer similar exposure.
- Ask what you receive for each layer of cost, and whether you could get it more cheaply.
Watch out for: Dismissing a 1% difference as trivial. Over decades, small recurring costs compound into a large share of the outcome.
Distinguish volatility from loss
Volatility is how much a price moves around. Permanent loss is capital you do not get back. Confusing the two causes some of the most expensive investing mistakes.
- Expect declines. Broad equity markets have repeatedly fallen 20% or more and later recovered.
- Decide your response to a decline while you are calm.
- Use volatility to judge position size, not to judge whether an investment was sound.
Watch out for: Turning temporary volatility into permanent loss by selling at the bottom, or by using borrowed money that forces the sale for you.
Think about downside first
Before asking what you could make, ask what you could lose and whether you could survive it. Protecting against ruin matters more than maximising an expected gain.
- For every holding, describe the realistic bad case and the worst case.
- Check whether the worst case would derail the goal the money is for.
- Prefer outcomes you can withstand being wrong about.
Watch out for: Plans that only work if nothing unexpected happens. Something unexpected always happens eventually.
Treat leverage with caution
Leverage is investing with borrowed money. It multiplies gains and losses, and it introduces the risk of being forced to sell at the worst time.
- Understand exactly when a lender or broker can demand repayment or liquidate your position.
- Remember that leverage can sit inside products — some funds, notes, and ETFs are geared internally.
- Stress test with a sharp price fall and a higher interest rate at the same time.
Watch out for: Leverage that appears cheap in calm markets. Its cost arrives all at once during stress.
Price matters — understand valuation
Valuation is the relationship between what you pay and what you receive. The same investment can be sensible at one price and unsound at another.
- Compare price to something fundamental: earnings, cash flow, rent, assets, or book value.
- Look at the range over time rather than a single figure.
- Write down the assumptions a price implies, then ask whether they are plausible.
Watch out for: Justifying any price because the story is exciting, and treating a high valuation as proof of quality.
Learn to read financial statements
Three statements describe a business: the income statement (profitability), the balance sheet (what it owns and owes), and the cash flow statement (actual cash movement).
- Start with the cash flow statement — cash is harder to present favourably than reported profit.
- On the balance sheet, look at debt, maturities, and whether short-term obligations are covered.
- Read the notes and accounting policies; significant issues are usually disclosed there.
- Compare several years to see the direction of travel.
Watch out for: Relying on adjusted or "underlying" figures without checking what has been excluded and why.
Do your own due diligence
Due diligence means verifying claims independently before committing money — about the investment, and about whoever is offering it.
- Read the primary documents: prospectus, offering memorandum, or annual report.
- Confirm that the firm and the individual are properly registered or licensed with the relevant regulator.
- Verify custody: who holds the assets, and who can move them.
- Write down what you know, what you assume, and what you cannot verify.
Watch out for: Substituting someone else’s conviction for your own work, and mistaking a polished presentation for verified facts.
Recognise fraud and pressure tactics
Investment fraud usually shares a small number of recognisable features. Knowing them is one of the highest-return skills an investor can have.
- Treat guaranteed or unusually steady high returns as a warning sign, not an opportunity.
- Be suspicious of urgency, exclusivity, secrecy, and pressure to act before you can verify.
- Never send funds to an individual, a new account, or a payment address supplied over chat or email without verifying through a known channel.
- Check the firm and the person against the regulator’s public register before transferring anything.
Watch out for: Affinity fraud through friends, colleagues, or community groups, and any difficulty withdrawing your money — a classic late-stage signal.
Manage your own behaviour
The largest gap between an investment’s return and an investor’s return is usually behaviour: buying after gains, selling after losses, and changing plans under stress.
- Write your plan down in advance and make changes on a schedule, not on impulse.
- Automate contributions and rebalancing where you can.
- Reduce the frequency with which you check prices.
- Keep a short log of why you bought something; review it before selling.
Watch out for: Fear of missing out, revenge trading after a loss, and confusing activity with progress.