Your roller blades should fit you comfortably and respond to your every move. Make sure your toes touch the front of the boot so that it can support your ankles and legs well. Roller blades with laces fit more snugly than the ones with buckles. But with buckles, it is easier to get in and get off. So choose carefully, depending upon your level of comfort.
The size, quality and manoeuvrability of your roller blade wheels are extremely important and these are the ones that influence your experience. The sizes of wheels range from 72 mm to 78 mm in diameter. Some of them even come with 80 mm. Roller blades with short wheels make for easy manoeuvrability and they are more stable. But one disadvantage is that they are slower than the skates with bigger wheels.
Most roller blades gears come with 78A wheels. They are considered as soft wheels. Whereas, 82A and 85A are considered are hard wheels. If you are aiming for skating indoors, then consider skates with hard wheels. Else, go for soft wheels for outdoor skating.
If you want to go fast, speed-skates are for you. They, too, are made of leather and come with five wheels. But mind you, they are not as manoeuvrable as other skates.
If doing tricks like grinds or rail-slides is your thing, then go for aggressive skates. They come in two categories: street and competition. They have shorter wheels and a wider frame to give you more control.
Roller blades come in many different varieties. Roller blades with light metal frames are faster and durable, but they could be a bit expensive. So choose them carefully, depending upon your priorities. In the end, whatever you choose, make sure you also buy the right safety gear like helmet and avoid brain injuries.