Pre Duplicity, Maul should only be used if you have an excess of Force and you KNOW that you won't need more force, so times like when the enemy needs just 1 more big hit to die, otherwise you shouldn't be using it.
Post Duplicity, Maul should only be used on Duplicity procs, which is 100% with spike and low blow, but you won't get duplicity til high 20s, and low blow after 29.
You'll find that fully stacked shock or discharge rival maul in damage pre duplicity, and that thrash isn't actually that far away.
Before you get voltaic fairly late into the game, thrash will be the main skill you'll be spamming, if you're deception, shock when you have 2 stacks of induction, discharge when you have 3 charges. Talented blackout as soon as you're sub 50% force and you know you'll need more.
For burst, wait until you have full stacks on discharge, Use recklessness, discharge, shock with induction stacked. This should cause a force crit on one of those 2 skills, which would proc the crit % chance talent in madness tree, which lets you then thrash/maul crit for a few seconds afterwards.
Hope this helped, I'm a noob too but I've done my fair share of reading up on Deception Assassins