Interesting question. I am currently reviewing my college calculus with
Dana Mosely lectures. I think he is an amazing teacher. I am going to watch his college algebra lectures as well. I'd recommend watching all of his stuff and doing some practice problems in algebra, trig, and calculus every so often to stay sharp mathematically.
Do you know exactly what courses you are going to be taking? Probably Calculus I, Physics I, Circuit Theory I and some fluff courses. If you have the time you could study all of those things. Ideally find out what textbooks the instructors teach with and get those. Also get a copy of The Art of Electronics (Horowitz and Hill), a decent multimeter, an old oscilloscope, a decent soldering iron, and find yourself an electronic project to build from a schematic. Or even better start designing your own simple circuits while reading Horowitz and Hill. I'd also recommend reading the allaboutcircuits online ebook and look at their forums for project ideas and for occasional help when you get stuck.
You should also get familiar with software. Start learning how to run circuit simulation and PCB layout software like Proteus, Tina, Orcad, LTSpice, Multisim, and Pspice.
MIT has first year Physics, Calculus, and Circuit Theory courses on their web site. Watch them.
And if you don't already have one, get yourself a good programmable calculator. I used an HP48SX in my university days. I'd recommend an HP48G or HP48GX from Ebay. You might also consider an HP 50G if you plan to write a lot of programs. It has a much faster CPU than the 48 series (although some speed is lost on emulation), but it has a 'slow' keyboard. I can enter a problem noticeably faster with the HP48 clicky keypad than with the newer models and speed is everything on exams. You may already favor TI, but maybe you've never tried one of the older HP designs from before HP just started apeing TI's design.