theres lots of techniques.
controlled reps are the most effective, smooth motions up and down.
drop sets can be effective, that is explosive up, slow down. breathing technique is important here.
high rep sets are also effective for muscle toning and endurance, up and down at a quicker pace than normal, still in a controlled manner, 10 - 20 reps.
cheat reps are ones performed at the end of a set, where you compromise your form to power out a couple more reps. even though they aren't controlled or isolating they can help give that extra pump that builds new muscle.
the one habit you want to get into is isolating the muscle you are trying to work. as in. it should be doing all the work. don't assume you should lift 40s because you can, you would be better to lift 30s in a controlled manner.