First, practice matching the little pictures of airplanes to pictures of a horizon featuring water and land. That's all spacial perception, like visualizing stuff, and understanding where you are- there is a whole section just on that, and I think it is probably important for the PFAR, since pilots need to be able to quickly figure out where the hell they are and where they are going. That section is also important because you probably don't have any other experience doing that, and it's easier to improve than your vocabulary or trigonometric skills. Second, dude, don't be discouraged by this, but practice up on those math problems- word and geometry. The geometry practice will snowball and help you with the spacial stuff, probably. Finally, know just really basic stuff about flying, but you probably already know that.
Most importantly? Practice what you think you are bad at. Its always easiest and best to strengthen the weakest link. Good luck to you and- as you always say- do not get discouraged: look at each section as a unique opportunity to prove your intelligence.