Here's some advice...u_turn23:Definetly Any advice is good advice if iterpeted correctly.
Get several dives under your belt before you start messing with a speargun. As you've already learned in your class, Scuba is an equipment intensive sport, and adding equipment should be done incrementally. Get used to using the basic kit before adding to it. Concentrate on perfecting buoyancy control.
Practice finding and approaching fish without the spear; learn to identify them, learn to size them. Go with an experienced spearo & watch technique - also pay close attention to how much the fish shrinks from the time it is shot to the time it comes aboard the boat
Find and catch a few lobster.
While you can get a gun for your first spear, I personally recommend a pole spear first. If you can learn how to be successful with a pole spear, a gun will be a piece of cake. Besides, the pole spear's cheaper and easier to use (notice I didn't say easier to get fish with).
Start with smaller fish until you get competent with getting good kill shots; a big fish can whup you in a heartbeat.
Have fun... and welcome aboard.
Rick