The size displayed on climbing shoes only very vaguely corresponds to the size of your casual footwear, let alone your foot. Sizes vary greatly between brands, models of that brand and occassionally even two pairs which should be identically sized, thanks to the handmade nature of many rock shoes. Unless you are familiar with a particular shoe it is always best to try rockshoes on in our store where you will get a better idea of fit, comfort and potential for stretch.
Seeing as there is only a very marginal difference between stickiness of climbing shoe rubbers, the best shoe available is the one that fits best. As a rule of thumb, beginners should find a shoe with a fairly stiff sole which will feel more supportive on smaller footholds. Toes should touch the front of the shoe without feeling squashed and there should be minimal ‘dead’ space within the shoe.
Elitists may opt for a highly asymmetric, downturned climbing shoe with toes pushed hard into the toe box for optimum toe power, precision and the ability to keep their body close to the rock on very steep terrain. These are generally only used for bouldering or extremely technical routes where the rock shoes will come off between climbs. Always try to fit rock boots towards what they will spend the majority of the time doing, whether it be trad climbing, sport climbing, bouldering or huge multi pitch routes in the Alps. Those stickies you used to send that V14 boulder problem may well cripple you on the descent from Raven Crag in Langdale!