Before buying boots the most important question you need to ask yourself is what you want to do in the outdoors and when you want to do it. This will help you decide what style of boot you need. Most quality boots are still handmade and built on a last (specific fit and shape of boot) and will be designed to fit a variety of shapes of foot from women’s and men’s feet, thin to wide feet and also low and high angle/arch support. Other attributes to consider are waterproofness, durability, breathability and weight. However something that is often overlooked in footwear systems are socks and footbeds. The best fitting and most expensive boot could still cause problems if combined with an old pair of thin cotton socks you’ve worn for the past 10 years! Overall fit will be a descending factor in your purchase, the best looking boot you’ve had your eye on for the last year may not fit you shape of foot.
The start point in fitting the boot is to ensure that you have the right size and remember that it is possible to customise the fit of a boot that is slightly too large but it is virtually impossible to do anything about a boot that is too small. If in doubt go for a size that is slightly large rather than one that is too small. Bear in mind that the critical size element is the length. Boots will often give or can be modified in width terms but it is virtually impossible to modify the length of a boot. When trying the boot on make sure you do so with your usual sock combination. You should also bear in mind the end use of the boot. For example if you are going to use your boots when you are likely to be carrying a heavy rucksack then this will alter the loading and shape of your foot. You should therefore try wearing the boots with a loaded sac on.
Climbing shoes aren't the most comfortable type of footwear. They should not be so painful that you can’t bear to have them on after short move nor should you want to keep them on in the car on the way home. Beginners seeking advice on their first purchase are generally told to go for a tight fit, and buy smaller than their usual shoe size. This is ok as a general rule but climbing shoes vary massively in shape and size so it is always important to try them on in a shop.
It's better to have slightly more space than you need than to be in agony all day. Although you might start climbing on an indoor wall, bear in mind that later on you could be doing full day sessions out on a crag. You'll also have to do some walking or scrambling to get from the top of each climb to where your comfortable approach shoes await you at the bottom. Generally socks are not worn with climbing shoes but if you want to climb early in the season or early in the morning in winter at your climbing wall, socks are acceptable but remember this will affect the fit of your shoe.
The main arguments between a Velcro shoe and lace up are fit and speed. Some say you can fine tune a lace up shoe better than a Velcro, however this does depend on the fit of your shoe in the first place. It is a lot quicker popping off Velcro shoes between routes than a lace up and lets your session/day run much smoother.
Some climbing shoes bunch your toes up inside them, rather than letting them lie flat. The reasoning behind this is that the greater the curve of your toes, the stronger they are (just as bending your fingers enables them to take more load than if they're straight). You can spot these from the way the toes curve inwards, and you're more likely to use them for technical, and more advanced, climbing. Beginners on the other hand are more likely to want symmetrical shoes, which have a last that's less claw-like, and more ... well ...foot-shaped.