New Mesmer here
This thread will help you make/chose a build and give you plenty of other useful tips regarding the mesmer class. End game wise you can do whatever you want as a mesmer, you are not restricted to just one aspect of the game, it’s just what you want to do.
https://forum-en.gw2archive.eu/forum/professions/mesmer/Guide-Lyssa-s-Grimoire-The-Mesmer-Handbook/page/3#post2994314
The Corrupt Mesmer Builds
Mess around till you find something that looks cool?
The basic mesmer playstyle is basically:
1) Pick a target.
2) Summon a bunch of illusions
3) Attack with your other skills
4) Shatter illusions when it looks like damage will be enough to drop the target
There are different variants of course (you could build purely for clone generation to get lots of shatters, or set up for condition damage so clones deal decent damage, or just straight-up focus on phantasms for raw DPS) but it’s a bit early to worry about that at level 22. Sw/Sw + Sw/P is the dungeon standard because phantasm builds are extremely powerful and build up to incredibly high sustained numbers against dungeon healthsinks but against trash mobs where the 3-4 seconds needed to get phantasms up is considered a slow kill, it’s not necessarily ideal.
Dont be scared of the forummesmers around here either. If you like GS feel free to use it as one of your weapons. GS + SW/Pist or Focus are great for phantasm builds.