Ok, so the Jab Cross Hook techinque is pretty basic but I want to make sure I've got it down right. The jab goes straight forward. The cross, torque your body and move you hand across. The hook, torque the right(left) side of your body and strike either with the elbow or fist...

Jab opens the defense of the opponent, and can be a defensive jab. Hook usually follows a jab, then rear cross. Footwork and timing and bodymechanics which you seem to understand already. All boxers use these punch but how many land or connect or throws self off balance. See jab cross hook combination as part of tactics see link for mechanics.
hope this increase lightining Jab hook cross combination.

http://seaford.abc.users.btopenworld.com/mechanics_of_punching.htm

Pak sao? Hook before Cross? Hook is used in close fighting, cross is more longer range. You'd have to push them or something before you could use a cross.

Both the hook and the cross can be thrown at a variety of ranges.

Make sure that your jab and cross go straight down the pike unless there is a reason for doing otherwise. The tactical placement of your blows in relation to your opponent's hands is a hard learned but valuable skill.