Drink lots and lots of coffee because you will work like you have never worked before and keep hours which are unGodly!! Also get a friend to proof and edit all your work. On average the typical grad student writes 200 pages publishable text each semester. Keep a lot if ink cartridges around.
I taught grad school so no original thoughts and definitely no whining. If you can not take it quit but do not become so self absorbed and needy that your are dreaded.
Also you have a syllabus. Stay ahead on your work, research, studying and paper writing. Since you know what is coming there is no reason to ever fall behind!!