I personally don’t recommend spending the money on Rapid Viz. It’s not expensive, but I find a lot of it borrowed from other sources.
You can get a good bit of the tutorials from drawthrough.com actually. Well, perspective is the most important thing you need to grasp. If there is a perspective class in your school, take it and make sure you put in lots of effort into it. BE patient, it may be boring but you won’t regard it.