Techniques:

Swinging:
The most basic movement is of cource swinging.
Use the hook to grab a wall and let the laws of gravity do the rest.
Useful in most turns.

Running: 
In long tunnels hook the floor or roof and quickly release it.
The hook will give you the pulling speed, but watch out! If you
hold for too long it will pull you back and youll lose your speed.

Climbing:
The same way you can use the hook for running you can also use
it for climbing, hook in a 50-60 degree angle and let the ropes
pulling force pull you up, release and hook again and pull yourself
further up until youre at the top.

Grabbing, tossing:
In the heat of a race it may help to grab an enemy to slow him/her down.
With a little more finesse you can grab or toss players while theyre
in the air to make them miss their target and fall.


Only for maps with grenade launchers:

Rocketrunning:
To get maximum boost shoot a rocket just behind you,
the splash will give you high speed but watch out!, you'll take damage :).

Rocketjumping:
This one is just like the rocketrunning, but a little trickier.
Jump and shoot in the ground at the same time to boost yourself up in the sky.
By having the right angle you can get very far with very high speed
but a lot of training will be needed ;).

Rocketboost:
In a few maps, (those where you start with a lot of armor), you can
quickly eject yourself from the starting lane by simply moving in the correct
direction and shooting immideatly into the wall right next to you.
If you do it quick enough, you will pick up additional armor, so that when
you come out you will still be at 10/10.