The Hook and Toproll are the most common techniques in armwrestling, followed by the press and the variations of a hook or toproll.
But there are some other techniques like the the sweep or "dead wrist".
To be a good armwrestler you need to find the things that suits you the best. Since everybody are different when it comes to strenght both in muscles and tendons and the way we can move our joints and so on.
Practice hard and feel what is best for you.
The sweep:
Simply put it is a move where you just keep your hand/wrist looked and only move fast to pin your opponent.
It is all about sidepressure.
Shown here by Brzenk.
The "dead wrist"
A variation of the press / shoulder roll.
Here you don't keep your wrist looked, instead you "loose" your wrist but keep pressing to pin your opponent.
Sort of a back up move and something you should use carefully so you don't hurt your wrist.