First time I ever did a simple trick for my girlfriend I thought I would have an heart attack. I felt the adrenalin, and suddenly it was over and she looked at me, surprised with "her" card in her hand I can't even remember my patter, I just did it and somehow it worked. I was shaking. I took her hand and put it onto my chest and she was shocked at how fast my heart was going
since then this happend every time I performed for someone (that first time was about two month ago), but it's getting better. I think it's best to do just one trick at first, with short patter and after some time and building up some confidence start to do longer routines. babysteps

it's totally stupid, I know. especially when the spectator is my girlfriend and she knows almost everything about me, good and bad. but it just happens. everyone can get over it. it may take some time, sure. but hey, everything does and everytime I find the card, let the tomato levitate or whatever, I know that it's totally worth all the anxiety.

Epithany...Nervousness is part of the "schtick". I remember reading of MANY of the bright stars of the art, noine the least being Blackstone, Sr. and, if you read the life of Cardini, he too had moments of concern prior to "going on".
This nervous reaction only helps to condition you for the performance if handled
with the right disposition.

If working for a large audience, think of them as so many "heads of cabbage" in a cabbage patch. Funny, yes, but can be a great help.

Another piece of advice I have used. Carry a small mirro with your props. Prior to your entry, look into the mirror, state to yourself, "I AM Very Good".
Then make yur appearance.

Hope this will add to advice of others in this post which are also vey good.
Success is what yu make of it! Break a leg.