“What should I do before general anesthesia?”

The first thoughts I have in answering this question is to say first, take all of your routine medications as they were prescribed, unless your anesthesiologist tells you otherwise in a pre-operative evaluation (which should be done days before the procedure, not at the last minute). Be sure your anesthesiologist knows everything about your health, and any medical problems you might have. DO NOT EAT any solid food for at least 8 hours prior to the procedure. The optimal preparation also include staying away from any smoking materials for at least 2 weeks.
Many anesthesiologists feel it is OK to drink any clear liquid (one that you can read a newspaper through a glass of it) up until 2 hours prior to the administration of anesthesia, but while this could be discussed and requested, it should be up to the anesthesiologist who is responsible for your anesthesia to decide in your particular case if this is appropriate or not.
It is not possible to make statements which cover everything that an individual should or should not do prior to any administration of anesthesia for any type of surgery. That's why the best advice is for you to discuss what you should or should not do with your anesthesiologist for your surgical procedure. in answer to this question, I can provide only generalizations that must be "fine-tuned" for the surgical procedure.

Don’t eat anything after midnight. Your surgical staff will discuss what medications you should take or avoid and when to stop clear liquids for safety.

From Christopher Creighton

Do not eat or drink anything after midnight the night before surgery, except for certain important medications (beta blockers, diuretics, antihypertensive medications), but do not take ACE inhibitors or ARB's as those drugs interact with general anesthetics to cause profoundly low blood pressure.