Olive oil is forgiving, but easy to get subtly wrong. A bottle bought with good intentions can taste flat within months — not because the oil was poor, but because of how we stored it and when we used it. Here are the mistakes I see most often, and the simple habits that fix them.

Storing Your Oil Beside the Hob

The kitchen shelf next to the hob feels like the natural home for a bottle of olive oil. It's within reach, it looks the part, and it saves a step when you're mid-sauté. Unfortunately, it's also one of the quickest ways to ruin a good bottle. Heat, light and air are the three enemies of olive oil, and a spot beside a working hob delivers all three in generous measure. Every time you boil a pan of pasta or sear a chicken thigh, the oil in that bottle warms, and warmth accelerates oxidation. The result is oil that tastes flat, slightly waxy or, at worst, faintly of crayons.

Store your everyday bottle in a cool, dark cupboard away from the oven, and keep a small decanter or a 250ml bottle on the counter for daily use. Refill the small one from the big one every week or so. If you have space, a low cupboard on an external wall is ideal. Dark glass or a tin protects the oil from light, which is why many good producers package in tinted glass or metal. If your oil came in a clear bottle, consider decanting it into something darker or keeping it in the box it arrived in.

Judging a Bottle by Its Colour

Colour tells you very little about quality, and yet it's the first thing most of us notice. Bright green oil looks vibrant and fresh; golden oil can seem thin or less serious. In reality, the hue of olive oil depends on the variety of olive, the ripeness of the fruit at harvest and the pigments present — not on how well it's been made. A deep green oil might be young and peppery, or it might simply come from early-harvested olives with plenty of chlorophyll. A pale gold oil from a different variety can be every bit as complex.

What matters far more is flavour and aroma. Pour a teaspoon into a small glass, warm it in your hands, and smell. You're looking for fresh, grassy, artichoke or tomato-leaf notes. Taste it: a good oil will have a peppery kick at the back of the throat, a sign of the polyphenols that also help preserve it. Bitterness and pungency are positive qualities in a finishing oil, not faults. Cloudiness is also not a reliable indicator; some excellent oils are filtered, some are not, and a cloudy oil can simply be unfiltered rather than inferior.

Assuming Country of Origin Tells the Whole Story

It's tempting to reach for a bottle from Italy, Greece or Spain and assume you're getting the best. These countries have centuries of olive-growing heritage, and many superb oils come from them. But country of origin on the label doesn't guarantee quality, freshness or value. A bottle may be labelled as a product of one country while blending oils from several, and the harvest date — often far more useful — is sometimes buried in small print or missing altogether.

Instead of buying on nationality alone, look for a harvest date rather than just a best-before date. Olive oil is a fresh product, not a wine that improves with age. Oil from the most recent harvest, pressed within the last twelve months, will taste livelier than a bottle that's been sitting in a warehouse for two years. Single-estate and single-variety bottles can be wonderful, but they're not automatically better than a well-made blend. Taste widely, buy from producers who tell you where and when the olives were pressed, and let your palate — not the flag on the label — guide you.

Hanging On to a Stale Bottle for Finishing

We've all done it. There's a quarter-bottle of something ordinary at the back of the cupboard, and you use it to drizzle over a tomato salad because it seems a waste to open the good stuff. The trouble is that a stale finishing oil can drag down an otherwise lovely dish. Finishing oils are used raw, so their flavour is front and centre, with nowhere to hide. If the oil tastes dull, musty or faintly of cardboard, it will taste that way on your plate.

Use older or less characterful oil for cooking, where heat and other ingredients will mask its shortcomings, and keep your best bottle for drizzling, dressings and finishing. Better still, buy finishing oil in smaller bottles so you actually get through it while it's fresh. A 500ml bottle may look like better value, but if it takes you a year to finish it, you've lost the freshness you paid for. Decant a week's worth into a small bottle and keep the rest sealed and cool.

Using the Wrong Oil for the Job

Another common mistake is treating all olive oil as interchangeable. Extra virgin olive oil has a low smoke point relative to refined oils, though it's more stable than many people assume, and it's perfectly happy for gentle frying, roasting vegetables and sautéing at moderate heat. For deep-frying or very high-heat searing, a refined olive oil or a different oil entirely may be more practical. But for most everyday cooking in a UK kitchen — onions, garlic, a tray of peppers, a piece of fish — extra virgin works beautifully and adds flavour as it goes.

Where people go wrong is the reverse: using a cheap, neutral oil for a dish that cries out for the character of a good extra virgin. A bowl of beans, a plate of grilled bread, a tomato salad, a bowl of soup — these are dishes where the oil is a seasoning, not just a cooking medium. Match the oil to the job.

A Few Habits Worth Adopting

Small changes make a big difference over a year of cooking.

• Buy smaller, more often. A 500ml bottle you finish in three months beats a 1-litre bottle you keep for eighteen.
• Check the harvest date. Fresher is better, and the date is more useful than a best-before.
• Store cool and dark. Away from the hob, the oven and direct sunlight.
• Keep a decanter. A small bottle for daily use means less air and light exposure for the main supply.
• Taste before you finish. If it smells dusty or tastes flat, move it to the cooking shelf and open something fresher for the table.

None of this is complicated, and none of it requires spending more. It's mostly about treating olive oil as what it is: a fresh, perishable ingredient with real character — not an indestructible kitchen staple. Get the storage, the freshness and the job-matching right, and you'll notice the difference in everything from a simple tomato salad to a slow-roast tray of vegetables.