Okay, so you have the size of your head, so what about the shape of your face?
Before you go off to buy a wig you need to get some background information.
The first essential bit of information is the shape of your face. Is it an oval face? A round face? A square face? Heart-shaped?
If you do some research on Google you should find plenty of websites and pages with oodles of fashion tips on hairstyles which suit each particular shape of face.
This information, together with your personal preferences, the natural colour of your hair, and everything else will help you to determine the Bottom Line when it comes to buying a wig - which is no different from buying any other item of women's clothing or accessories..
LENGTH - STYLE - COLOUR.
However with wigs you also have to decide between Natural and Synthetic.
Synthetic wigs are cheaper of course. You can find a decent synthetic wig from just £20 in the right places (more later) and they come usually pre-styled, and require very little maintenance. I would make sure that the fibres are at least 80% Kanekalon as Kanekalon is stronger, looks more natural, and can take low amounts of heat (in case you do need to style it).
The downside of synthetic wigs is that they tend to 'frizz' with a lot of wear and they retain more heat between the scalp and cap which makes them somewhat more uncomfortable to wear in hot weather.
Or you can go for Natural hair, which is usually Indian Remi hair (human hair) though some cheat and blend human hair with the hair of a yak. Prices for natural wigs start at £80 and up - though you can sometimes find bargains from just £50, depending on the style and length.
The big advantage of Natural or human hair wigs is of course they look totally natural and the hair behaves pretty much the same as anyone else's hair. You can also do stuff to Natural wigs that you can do to any hair, use normal shampoo, conditioner, and (unlike synthetic wigs) you can safely use normal hairspray.
But there are downsides. One of them is that, unlike the hair on your head, the hair which is lost through combing and brushing doesn't grow back. I wouldn't recommend anyone using a comb on a natural wig and you have to be careful about what sort of hairbrushes you use. Natural hair wigs also require more maintenance and care than synthetic wigs. You have to be careful of matting, especially in the nape area of the neck, and natural wigs tend to degenerate somewhat quicker than synthetic wigs with regular wear.
The other thing you need to think about is the cap construction. Usually a wig has hairs sewn onto a cap made of wefts which usually comes with a fringe which hangs down over the front of the cap to hide the wefts. In windy weather your hair blows all over the place and with some wigs this can expose the wefts and with it, the fact that you're wearing a wig.
You can get round this with a 'lace' wig - usually a lace front wig or a full lace wig. On a lace wig you still have the cap made up from wefts, but along the front (in lace front wigs) and also around the nape of the neck (in full lace wigs) you have hair sewn into a fine lace cap which can be cut and styled to suggest a natural hairline, so you can sweep the hair back over your head away from your face.
Price wise there's not much difference when it comes to synthetic wigs but when it comes to natural wigs expect to pay around a £100 more for a natural lace front or full lace wig.
Okay, so where do you buy your wigs from?
I'm of the opinion that the best shops to buy a wig from are the ones in larger cities usually owned by Asians and frequented by mainly black and African women. Usually these are shops which don't just have wigs but also tons of hair care products and they're generally also really good places for stocking up on decent quality cosmetics and costume jewellery.
You can of course buy a wig online, e-Bay being a good place, but I would strongly recommend buying your first couple of wigs in person or at least until you have a good idea of what style, size, colour and stuff of wig suits you best.
Buying a wig can be daunting, frustrating especially if you make the wrong choice. I write from experience and can cringe when I think of the couple of earlier purchases which weren't fit for even use as a lavatory brush. Research helps you make informed choices.
However, if you know any hairdressers who are friends..