Honestly, there isn't much else once you get through both volumes of Polchinski. You could try reading GSW or BBS for alternative perspectives. Anything beyond Polchinski is research level and at that point, you only learn what is specifically needed for your research.
– PraharJan 09 '23 at 16:03
Possible duplicates: https://physics.stackexchange.com/q/27760/2451 and links therein.
– QmechanicJan 09 '23 at 16:30
1
Start writing a solution manual to the problems from his two volumes which as of yet don't have solutions published in the web.
– MathematicalPhysicistJan 10 '23 at 20:04