I don't have much to add to what was said, especially since I'm going through the fundamentals myself.
I can tell you that I finished the level 1 of the curriculum at svs, and although now I need to practice all the fundamentals I learned there a lot, the improvement and change in the way I draw was outstanding. I am actually surprised with how much I evolved and got better in 3 months of just following the courses and doing each exercise, and in some, taking the time to practice it over and over again.
So, just to say that going back to fundamentals, no matter how simple the exercises seem to be, and taking the time to practice them does pay off a ton!
And regarding the getting used to the tablet, doing line exercises (like the ones in How To Draw Everything, by Jake Parker at svs), although boring has hell lol, can help a lot with getting a better line control on the tablet.