The best way to learn thief is to experiment with all the weapon sets and utility skills. Also, thieves behave a little differently than other classes. Their weapon abilities don’t have cooldowns but use up a resource. Their #3 skill also changes depending on both the main and off hand weapons equipped. The #1 skill changes when in stealth. When out of combat you can view your weapons stealth attack when hovering over the #1 icon.
Some generic tips:
1) Teleports without a cast time won’t interrupt your current animation. You can _use steal as a gap closer while casting #5 with offhand pistol or dagger for example. You can also begin pvp stomp animation, teleport away with Shadowstep, then use the skill again just as the stomp animation is about to finish.
2) Sword and short bow are your only cleaving weapons. #3 with d/d will hit multiple targets. You can also trait for bouncing pistol bullets (Trickery X).
3) In most PvE settings, Signet of Malice is the goto heal. The healing proc doesn’t have a cooldown so the more you can proc hits the faster you can heal back to full health. You might want to switch to Hide in the Shadows for condition cleansing boss fights. For PvP, Hide in the Shadows and Withdraw are usually taken.
4) Short Bow has a spammable blast finisher which makes it a really useful weapon to have at all times. Fields to look out for are fire (aoe might stacking), water (aoe healing), and lightning (aoe swiftness). You can also stealth an entire group without using Shadow Refuge by using the blast finisher on a smoke combo field. like pistol #5 or Smoke Screen.
5) For traveling purposes, Signet of Shadows is great for a passive boost. Shortbow #5 is a reliable teleport that can be used to make big skips, like up hills or to a bridge directly above. It doesn’t work in every location so you need to experiment. There’s a very useful trait under Acrobatics IV that gives you 20 seconds of swiftness whenever you kill an enemy. You can also trait for Trickery V and steal without a target to aoe buff swiftness.
6) Revealed is a debuff that prevents stealth for 3 seconds in PvE/WvW and 4 seconds in SPvP. If you attack someone from stealth, you’re revealed. If you let stealth run out, you don’t get the revealed debuff and you can restealth right away.
7) Caltrops and short bow #4 won’t remove stealth or reveal you.
8) Some things the tooltips don’t tell you. s/p #3 gives you evade frames but not enough to make the entire animation safe. Dagger Storm and the stolen pvp warrior item can be used to reflect projectiles. Shadow Refuge will remove stealth and reveal anyone that steps outside of the circle before the circle disappears.
9) Deadly Arts VII increases your damage by 10% when using a summoned elementalist weapon like Fiery Greatsword and Frost Bow. Afaik, it does not increase your damage when you have a stolen item.
10) You can disable an entire group of enemies by using pistol #5 every 4-5 seconds. Mobs with the Defiance buff (champs and bosses) won’t be affected by this.
Hope this wall of text helps!
edit: added 2 more tips.
