Generally you want to consider:
The shoe must be comfortable, we recommend laces rather than the bindings that can become brittle and break, unlike laces which you can easily replace.
The bearings must be of good quality too, there are different ratings based on the ABEC Scale (from 1 to 11 the higher the better) but also bear in mind the quality of the steel used, which is also important.
The wheels are made of polyurethane and their hardness is measured on the A scale (78A-97A -the higher the harder the wheel). Softer wheels are more grippy. Diameters vary from 59mm to 125mm - the bigger the wheel the faster it can go but you compromise on maneuverability.
Generally we suggest measuring foot from heel to big toe and adding around 7-12mm for growth. (If you are still growing)
Feel free to contact us if you have any questions or wish to order a pair. We can also order in most things if you have a special request so please don't hesitate to ask!