Ditto what Ganthor said. You should practice doing back covers if you want a challenge. Copy can be tricky, especially when provided by people who aren't thinking about what the finished product will look like -- there's either not enough or too much text. Couple that with a bunch of photos, and it's some serious work. It feels like some of the least creative work you will ever do in design, but it actually takes a lot of finesse to make it look good. Other design projects you might want to try: newsletters catalog page (or two-page spread) magazine page (or two-page spread) two-fold brochure business card book cover flat (back, spine, and front) etc.