What kind of skates?

There are many different kinds of inline skates :-

Recreational or general purpose skates. I suggest starting with this kind of skate, as it's a good all-rounder and is perfect for learning in. Don't choose a skate with wheels larger than 84mm

Aggressive skates. These are designed for the sort of skating you see on ESPN, with ramps, half pipes, and grinding. They tend to have small wheels and heavy padded boots, designed for protection and stability when jumping.

Speed skates. Optimised for skating fast, they tend to have longer frames, bigger wheels, and hard low cut boots. Much harder to skate in than other skate types.

Hockey skates. These have short and highly manoeuvrable frames, smaller wheels, and usually armoured boots to protect from puck impacts.

Fitness skates. Half way between recreational skates and speed skates, and thus a little harder to skate in, but also faster.

Slalom skates. Can be something of a mixture, usually a combination of hockey skates and recreational skates. Optimised for control and manoeuvrability.

What's most important when buying skates?

Fit and comfort. Skates come in all sorts of different sizes and fits, so you're best off trying several sizes of skate from different manufacturers until you find some that fit you. There's no rule such as "buy a size larger than your shoe size", since different skates fit different people differently.

Where should I buy?

I would strongly recommend going to a real shop and trying skates on. Fit is so important with skates, that it's simply not worth trying to save a small amount of money by buying online.

The Big Three

I'd recommend sticking to one of the big three manufacturers - K2, Rollerblade, and Salomon. This will help to ensure you buy skates of sufficient quality.

Budget - what not to do

Don't buy cheap skates, thinking you'll try skating before spending too much! This is false economy, cheap skates fit badly, roll poorly, and are the single most likely thing to discourage you from further skating. What's more, this type of skate works so poorly that I usually have to tell people that they need to buy new skates before having a second lesson.

I would suggest not spending less than £80 on a pair of skates, and leaving over some additional money for protective gear, usually knee pads, elbow pads, and wrist guards.  Top end recreational skates cost around £200, whilst high end custom speed skates can cost around £1000.