With Valentine's Day coming up, chances are you'll be ditching your mates for an entirely different evening with a woman. She'll be expecting a Valentine's Day gift of course. Perfume, chocolates, flowers and a great evening out. There are no hard and fast rules, but if you've been going out for anything longer than six months, you really ought to be buying lingerie for her. But it can be a total minefield - trust me, I've been there and got the t-shirt (the wrong size, first time round, of course). Profit from my pain with my top tips on how to buy lingerie. Course, if you want the female perspective, and why wouldn't you, check out Miss H's blog on lingerie.

Who's it for?

This might seem obvious but like so many things, what she wants and what you want are probably two very different things. You might be thinking tassels and peepholes, she's thinking about decent underwiring support and silk fabrics. So find the middle ground. Not least because I assure you, asking in-store for nipple tassels can feel pretty awkward...

When's it for?

You're a man, so you're going to be drawn to flamboyant (i.e. sexy) lingerie. This means lots of detailing, some rouched fabric, suspenders and, potentially, big bows. All of these things make it impossible for her to find clothes that look good over the top. But bland lingerie will have her showing you the door in no time. So look for quality fabrics, silk if possible, good cuts, with some interesting lace detailing - sexy not stuffy, sassy not hussy.

The details

• Sizing - you'll need to rifle through her drawers when she's not looking to find out her size. Look for ones she's worn recently, as these will be most accurate. If in doubt, for panties, go for a size smaller, for bras, a cup size larger - flattery will get you everywhere. Keep the gift receipt so she can change them if needed.
• Colours - the cliché is shocking red. You're not a clich&eacute kind of guy, so avoid. For paler skin, avoid pale colours like white, beige or even paler yellows - it's not a good look. Opt for black (safe) or colours you know she likes instead - turquoise, purple, green. For darker skin, bright colours (fluorescent orange) can work well.

Terminology

You'll face a whole dictionary's worth of terms, most of which you won't understand. Phrases like half-cup, balconette, plunge etc. It's like a different language. But don't worry, you're not meant to understand these things. Of course, if you have to take advice from the very attractive sales assistant then so be it - you've no other choice. Nervous amongst strangers? Just take in the superbly shot photography around the store.

The best tips I can offer you

• Only. Ever. Buy. Matched. Sets. Seriously. Individual panties, bras, mismatched sets - they're not quirky, they're a sign she couldn't afford the complete set (or, worse, that crazy Madrid weekend with Juan where she lost a bra somewhere in his hotel suite). Don't remind her of poorer times, crazier times, or look like you can't afford the complete works. Buy matched sets. Always. I learnt the hard way. If they're from a bargain bin, expect to find yourself in one soon after.
• Bras are a real hassle to clean. Buy her two matching pants for each bra, at the least - one French shorts, one g-string or thong, for variety and she's got two outfits from one bra. And you've got variation on the same woman.

Mr D's top five lingerie brands:

1. Calvin Klein Underwear - affordable, safe, a great starting point.
2. Elle Macpherson Intimates - classy, reasonably priced, different.
3. Simone Perele - they're ooh la la French classics.
4. Myla - the brand women aspire to. Expensive, sexy, up-front. Miss H swears by them (and in them, quite a lot.)
5. Pleasure State - interesting designs from Australia, great for prints, moderately priced.

Decent lingerie costs money. The fact you've bought her some will give you massive bonus points. And for that, you'll deserve a reward...