When buying a fork for your scooter, be aware that the fork fits your scooter.
By default, forks are 28 mm in diameter, unless otherwise noted.
It is important that you choose the right size fork that fits your wheels. All forks fit 100mm wheels and most can also be used for 110mm or higher - but you can read this under Additional Information, at the desired fork.

Quality:
There are also various kinds of qualities of scooters forks.
The cheapest is a Steel fork. This type of fork is very heavy and is usually found on the cheaper scooters.
If you are looking for a good quality fork, look for a Aluminum fork. These are much lighter than steel and are therefore seen on more expensive scooters.
However, there are 2 different types of aluminum forks; One-Piece and Two-Piece. Two-Piece is a cheaper front fork, and One-Piece is the most robust as it is cast in one piece of aluminum.

Compression System:
HIC - If your scooter uses HIC, the bar is most often oversized (32 mm internal diameter). This means that your front fork needs a Shim that you put on the front fork to achieve the 32 mm. This shim sits on some forks and can also be purchased separately here.
SCS - A scooter with SCS system uses either an internal diameter of 28 mm or 32 mm. However, this varies with the clamp / bar composition - Here you can use a Shim if your bar is oversized (32 mm internal diameter).