I would definitely recommend focusing on problem solving and the basic math (Solving systems of equations, trigonometry, differential and integral calculus) as preparation for future physics learning. Important starting points are learning to draw free body diagrams, calculating the force of friction on inclined planes, and newton's laws.

If you are beyond that already, I would recommend a firm grounding in Differential Equations. (The basis of 90% of classical physics and a good portion of quantum/relativistic physics up till group theory). Diff. Eq. gives you a peek into the nuts and bolts of physics that underlay the equations you are expected to memorize in early physics classes.

If you are looking for a source of math problems and explanations on the basic concepts, there are many books available. You could purchase an older edition from Amazon

(This is the one we used when I went to college, I paid $250 and now it's $15: http://www.amazon.com/University-Physics-Freedman-Francis-Weston/dp/0805391797/ref=sr_1_1?ie=UTF8&qid=1436124796&sr=8-1&keywords=UniversityPhysics11th+Edition )

or you could look for Open Source alternatives like the one here: http://www.anselm.edu/internet/physics/cbphysics/index.html

Good luck with your physics education!