Don't be afraid to write notes down, you can go up to speak with all the notes you need. However, at the same time, don't have a pre-written speech and just read that to us (we get enough of that at the Presidential debates!). Your speech should be off-the-cuff, which might be hard for novices but soon you will learn to master it.
Speak clearly and firmly, sometimes it's hard for people to hear you. Keep your feet planted. Make eye contact and keep a good pace--not too slow and not too fast. Don't worry, you will have time (a minute and a half) and the chair will give you warnings about your time progression with gavel knocks.