Pains me to say it, but this is exactly what it looked like for me from 20-ish->80 on individual mobs with D/D.
If 2 or more mobs, Shortbow autoattack and run in circles.
S/P for standing in the same spot and spamming Pistol Whip or just auto attack if you're uber lazy.
P/D for playing Whac-A-Mole with mobs (you're the pistol wielding mole ofc).
Thief can be really lazy to play in PvE. Often i see people spamming everything they got all over the place when it really isn't necessary - it will probably also get you hit more.