Re: Why is it that every time before i go on stage......
This kind of thing gets easier as you play more. It's perfectly normal. As you mentally condition yourself to be used to performing, it will become more natural to go out there and play with better state of mind. Going out in front of people and bearing your soul through your music is not a natural thing to do, so it's not surprising that you would be a little nervous at first. Just keep playing, and you'll get used to it. Remember, this is what you want to do, don't be afraid of it.
Also, caffiene and hunger will amplify this effect (both make you jittery). Avoid coffee before the show, and make sure that you have something in your stomach that will stay there for a while (something relatively heavy where you don't feel hungry anymore, but not so much that you feel full and bloated). Finally, if possible, try not to have a stressful day before your show. Take it easy, don't rush around, and try to keep a positive and relaxed state of mind.