<p>I made the mistake of buying them before I went to class. So don’t do the same and go to class first before buying them. Sometimes you may find out you only need to read a chapter out of a whole book and then you can simply go to the library or photocopy it.</p>
<p>But for science and math classes, I would just buy the books before. You pretty much need them for studying, problem sets, clarification, etc.</p>