Thief tactics
I was a pretty bad Thief but I’ve always been a creative roamer. I found the best way to initiate fights was by making sure you always see your opponent before they see you. I actually had someone party me once that I had fought about a dozen times and he complimented me on how well I was able to catch him off guard every time we fought.
Always use your “look behind” key, don’t be super aggressive when engaging people, never spam skills because initiative is important, even if it regenerates quickly, and before attacking someone try to be sure they haven’t seen you first. Even if they’re not stopped and waiting for you to attack, if they see you they still might have their finger on a button just incase. If they have no idea you’re coming, you can start the fight by cutting their health in half before they have time to react.
To answer your question though; I think it’s best to make people panic. Hitting like a truck is a good way to do that but resetting can have the same effect if you time your resets properly.
As a side note; maybe I’m just a sadist.. But I always had fun playing with people’s minds. Strike them from out of nowhere, run off leaving them feeling vulnerable, stalk them for a bit, strike again, then commit to the fight when they think I’ll just be running away again. Great way to cut someones health in half, let them think they’re safe because you’re just doing hit and runs, then actually finishing the job :P.
Champion: Phantom, Hunter, Legionnaire, Genius
WvW rank: Diamond Colonel | Maguuma