The main thing to remember when looking at golf shoes is that the sport involves a fair amount of walking, so you need to be fully prepared to spend a long time on your feet. If your toes ache or you get blisters, it will directly impact on the rest of your game. Therefore, a really quality pair of golf shoes will never be an investment made in vain and you should ensure that they fit correctly, not too large or too small. Otherwise, you'll be unable to concentrate on your swing because your feet will be throbbing and give new meaning to your handicap.
When buying this type of footwear, you can purchase your shoes in the same size you would purchase a normal pair, unless there is specific information to this effect given in the product description.
You'll also want to consider whether your golf shoes are waterproof or not. Many pairs come with a One Year Manufacturer Waterproof Warranty which will ensure that your feet stay dry, even when the weather does not.
The soles of your shoes will also have spikes to provide grip and stability as you walk and play. The majority of today's spikes are soft in order to keep the turf healthy, but grip the ground just as effectively as the metal variety.