1. Dress Code

Check if there's a dress code stated on the invitation. The event may require you to wear a cocktail dress or evening dress. Or there may be an unwritten dress code; if in doubt, make enquiries. You don't want to turn up wearing something completely inappropriate for the venue!

2. Try on with Shoes

Always try a dress on with the shoes that you'll be wearing, or the kind of shoes that you're likely to be wearing. If you try on a full-length evening dress without heels, you may find that it's the wrong length when you do put heels on. Trying a dress on with heels will also give you a better idea of whether it suits you; an evening dress won't look right without heels.

3. Appropriate for the Occasion

Also look for an outfit that is appropriate for the occasion. If it's very solemn or conservative, this isn't the time to wear something adventurous. It's also usually considered wrong to wear either black or white at a wedding, although these days the dress code can be more relaxed. And for a wedding, avoid outfits that will outshine the bride!

4. Take Accessories

If you want to pick something to wear with an item or items you already own, be sure to take them when you go shopping. It's important to try on pieces you may buy with your own items, or you risk buying something that doesn't look right.

5. Budget

It can be worth spending more for a very special occasion, although if you spend a lot you should look for a versatile piece that you can wear again. For a one-off occasion where you want to impress, consider hiring a dress. There are lots of online sites that will hire you a designer dress relatively cheaply. Or you could look at resale shops for a bargain, if your budget is limited.

6. Feel Good

For a special occasion, you'll want to wear something that makes you feel special. Since we obviously don't attend special occasions very often, we want to feel fantastic. So look for a dress that shouts out 'this is the one!' Remember that you can pick a fairly plain dress and let your accessories do the talking; a fabulous pair of shoes or an antique stole could be the thing that makes your outfit.

7. Allow Time

Finally, allow plenty of time to choose your outfit. Leaving it to the last minute means that you'll end up grabbing something quickly because you're running out of time. Bear in mind that you'll need to allow for delivery time if ordering online. You can order some very cheap prom dresses online from China, but be sure to order well in advance to allow for lengthy delivery times.

Take your time to choose your perfect outfit; dedicate a couple of afternoons to shopping for it. Don't shop for too long each time, or you'll get fed up and grab something. How much would you spend for a special occasion?