Hey im here to give you some example of the best skilling combos.
Lets get started :
First i advise you to get full 4 skill set, weps 4 skill and the latest rings.(if ur at least 70 get the bracelets 2^^) Note : Check my latest reply to check out the armors i think suit nicely for a good skilling session.
Go to an area with mobs that have a lot of hp(so u can combo like 12 Hits to kill the selected mob) and that you get 0 exp or around that value in order to just skill instead of skilling and lvling(the reason for that can be explained by people who are low ranked).

I tested some combinations of skills based on their cast/cool time and ive reached some interesting fast combos:

Blader : Assault(lv.9)>>> Impact Stab (lv.9) >>> Double Slash (lv.9)
My first Skill in less than 3 minute experience.

Force Blader : Force Assault(lv.9) >>> Impact Stab(lv.9)>>> Force Slash(lv.9)
Still working but that combo will do the trick

Force Shielder: Shield Charge(guess thats the name, lvl.9)>>>Impact Stab(lv.9)>>>Flash Draw(lv.9, can be another skill)Note: Use the Warrior Combo 2^^.

Warrior: Assault Skill(If thats the name, known by charge) (Lvl.9) >>> Impact Stab (Lvl.9) >>> Rising Shot (Lvl.9)
Note: Works for FS Aswell.

Force Archer : Freezing Arrow ( Lvl.9) >>> Aqua Arrow(Lvl.9) (Works fine those 2 in combo.)

Wizard : Do Freeze (Lvl .9) >>> Burning Hand (Lvl.9) >> (This 1 can be put out but good when u need to hit far) Magic Arrow (Lvl.9)

Gz to : kovyfive for Adding Warrior/Fa/Fs Combo.
Edit : Added jewel Armour Require For Fast Skilling, See latest Post.