Here are tips i have for successfully using a WRH that I have learned over time.
With Autotarget: the dash becomes your most powerful and dangerous attack because your dash will drive into enemies without roll off. That means single target damage but you have the greatest chance of all of the three dashes to hit. The downside is, the dash doesn't cancel attacks leaving you open to damage.
Without Autotarget: less damage potential due to rolling off a target because you aren't locked on a target. This is more defensive because you can slip around a lumber or other monster giving you time to attack or defend while they turn to face you. This is worse for turrets due to less damage and can push you a distance away giving the turret time to start shooting.
Third swing: the third swing is powerful and can cancel attacks, though it leaves you open a while and can be more trouble than it is worth if an enemie gets behind you. It has a good area and some knock back so can be used well against mobs or single targets but you run the risk of taking damage.
List your hints or tips below.
The number one tip I can give to people about using the Warmaster Rocket Hammer is to get used to using the "Shift" key to manually enable / disable autotargeting. My personal preference is to disable autotarget and turn it on with "Shift" as needed, allowing me to dash into enemies when I need to but doesn't send me into traps when I don't.
My second tip is use your extra mobility to your advantage. I like to use the dash to jump around between groups of enemies and pop them with the third swing before they know what's coming. The dash also helps me get out of range of an enemy's attack.
Third tip is if you're looking for crowd control, you're using the wrong weapon. Leave the crowd control for the Brandish and Divine Avenger users, or pack your own to use when you need it. The WRH truly shines when you use it to pick off the outlying enemies while the rest of your party is working on the others.
That's all I could come up with off the top of my head, I'll post more tips if I can think of any.