For quotes, go to the library and get a copy of Bartlett's Quotations. Very useful.
For the class, take it seriously, and ask your prof for extra feedback. Being a good public speaker has been important in every job I have had since college. Every one.
Tape yourself, at least audio, but video too if you have a video camera. Look for things like how many times you say "umm", where you seem rushed, where you pause too long. When I first started, I tended to talk WAY too fast and I suffered from the UMM syndrome, where every second of my speech had to be filled with my voice somehow, as if I was trying to "keep the floor" or prevent others from speaking over me. Learn to slow down--a LOT. Learn to pause purposefully and look out at your audience--later you'll use your observations to gauge audience reaction.
Learn to strike unnecessary words from your spoken language. "Got" should be avoided at all costs, it is a lazy word that has no real purpose. Get rid of it. There are others. Find them.
Learn grammar. Expand your vocabulary. Slow down.
Jim