Was re-reading this thread now that I'm intermediate complete to see how much still applied, and Kickflip's gouge is still spot on. I just wanted give some VNAV/T-1 advice while it's still pretty fresh.
For VNAVS (T-6 and T-1):
Learn the difference between compensating for winds, and applying corrections. As Hozer will attest, this tripped me up on multiple VNAVs. The way I like to keep them straight is that compensating is preventing the problem from getting any worse, (ie, you're 12 seconds slow, speed up five kts to prevent yourself from getting slower), while correcting is getting yourself back to where you should be (ie, increasing speed 25kts for 2mins to get back on time). Trust me, getting this down will prevent you from ping-ponging back and forth across your course line, and pissing off your pilot in the process.
For T-1s: Practice, practice, practice the checklists. Yes, they're a pain in the ass, and you'll never have to do air force style checklists again, but not knowing how to run trim/autopilot checks or the engine startup sequence etc.. sets a bad tone for the flight. It sucks not having a sim, but run them in the static mockup, and take full advantage of your FAM-0 to figure out how everything works.
Also, learn how to read the gauges, especially fuel. I can't tell you how many times I messed up fuel calcs in the T-1 because I glanced over quickly and read the gauge incorrectly.
That's all for now, I'll add to this if I can think of anything else.