In 1971, in a New York agency called McCann-Erickson, a 23-year-old junior copywriter named Ilon Specht was angry. She had spent her days writing ads that told women to colour their hair for men. So she wrote the Preference spot in a few minutes instead: a woman speaking straight to camera, ending on the line Because I'm Worth It. L'Oréal says it was the first ad to champion a woman's self-worth, and the line is still with the brand in dozens of languages.

I think about that every time I stand in front of a wall of boxes. L'Oréal hair color is one of the few drugstore categories with a real argument behind it: the choice belongs to the person with the hair. And the range today reads like three answers to three different wishes. Excellence is for gray coverage, Superior Preference is for fade defense, and Feria is for dimension and shimmer. The brand says Superior Preference lasts up to nine weeks and Feria comes in more than thirty shades, and I read both as claims to test on your own head.

The trick is to pick the box by what you want the colour to do, not by the model on the front. Excellence Triple Protection is where I would go for gray, and Universal Nudes is the ammonia free option for people who want a softer route. Superior Preference is the everyday shine one, and Feria is the fun one for a bolder brunette or a deep red. Then the between-colour helpers: Magic Root Rescue is the ten-minute kit for regrowth, Root Cover Up is the spray that lasts until your next shampoo, and Colorista's one-day spray is for trying a shade without a commitment. Colorista Bleach All Over is the starting point for going lighter.

Start with a strand test, whichever box you choose. Snip a small hidden piece near the nape, colour it, and wait for the full development time. It is the only way to see how your own base and your own previous colour will behave, and the brands themselves ask for an allergy patch test two days before you begin.

Outside the L'Oréal aisle, the options are more varied than most people expect. Madison Reed's Radiant Hair Color Kit is the full-colour choice, and its Root Perfection kit is the one to keep in the cabinet for regrowth. ColorWonder Demi-Permanent is gentler, and demi-permanent formulas fade instead of growing out with a hard line, which suits anyone who is nervous. Wella's Colorcharm is the salon-adjacent cream, and Clairol's Born Blonde is the one for going light.

For the days between, powders are the quick fix. Clairol's Temporary Root Powder and Color WOW's Root Cover Up Powder both brush on and come out at the next wash. Clairol's Total Root Touch-Up is the fuller touch-up, for when the regrowth line is bothering you every morning.

A pairing I like: a permanent colour every couple of months, with a powder for the week of a wedding or a big meeting. It stretches the time between boxes without making the gray look worse.

What I would skip: a root powder on wet or oily hair. It clumps, it turns muddy, and it transfers onto a pillowcase.

One rule for coloured hair: use cooler water. L'Oréal itself recommends a sulfate-free colour-safe shampoo, cooler water and heat protection to slow fade, and all three ask for nothing but a little attention.

The EverPure Bond Repair shampoo and conditioner are the simple starting pair, both sulfate free and made for colour-treated hair. From there, the mask is where dyed hair is happiest. L'Oréal Professionnel's Vitamino Color Spectrum is the one I would choose for a brunette who wants shine. Kérastase's Chroma Absolu is the strengthening choice for hair that has been coloured often, and shu uemura's Color Lustre is the hydrating one for the drier end.

Davines' MINU is for colour that has taken a long, careful appointment to get right. Virtue's COLORKICK is the mask that says it works on every shade, which makes it the safe one to share in a household with different colours. Ceremonia's Guava mask is for hair that is both damaged and dyed, and I like that it does not pretend the two are unrelated.

A habit worth borrowing: leave the mask on while you do everything else in the shower, then rinse with the coolest water you can stand. Ten minutes instead of two makes a visible difference.

What I would skip: a heavy mask on the morning of a fresh at-home colour. Give the colour a couple of days to settle before you load the hair.

Try this after your next colour: a gloss, not more colour. When hair looks flat a few weeks in, it usually is not the shade that has faded but the shine, and a gloss puts a little light back without another round of dye.

L'Oréal's Le Color Gloss is the in-shower option, and the brand says it lasts about ten days. The EverPure Glossing Lamination Mask and Glossing Conditioner are the ones for a weekly routine, and Elvive's Glycolic Gloss leave-in serum finishes the hair after a blow-dry. All of them are for people who want polish rather than a change of colour.

On the salon side, Kérastase's Chroma Absolu High Shine Gloss Treatment is for dyed hair that has dulled. Davines' Heart of Glass Sheer Glaze is built for blondes, and dae's Stargloss is the light finishing treatment I would keep at hand for photos. IGK's Mixed Feelings drops are purple toning drops for blonde hair, which is the tool for brassiness.

A pairing I like: a colour-care conditioner every wash, a gloss every second week, and toning drops for blondes once the warmth creeps back in. It is a small routine, and it keeps the colour looking like the day you did it.

What I would skip: purple drops on hair that is not blonde or very light. They do nothing helpful there.

I think the best L'Oréal box is the one you choose deliberately, and that is more or less what Ilon Specht was arguing in 1971. Pick by what you want the colour to do, test a strand, and read the timing on the box twice.

My routine would be Excellence for gray or Superior Preference for shine, Magic Root Cover Up in the bathroom drawer, EverPure at the sink and a gloss every couple of weeks. Then take a photo in daylight after the first wash, so you know what good looks like. She wrote it in a few minutes. You have a little longer to decide, and the shade is still yours. If you want to keep browsing, I also put together L'Oréal Mascara and the Paris Chemist Who Started With Hair Dye and Color Wow Hair Products.