I am a full time firefighter and my colleagues are perfect as they are so distrustful with my manipulations etc. If I can get away with things with them I can take on anything.
I visulize every move that I can but still at times get the shakes. How can I combat this? Is it just experience that I am lacking?

One amateur magish to another, I have had the same problem - it will eventually go away.
I suggest writing out a very simple set of lines (i.e. script) to go with what you are going to do. Scripting is very important, as it is really part of the presentation of the trick.
Also, practice to the point where you can literally almost do it blindfolded - then you will have the technical part down.
I am curious, what tricks are you trying? Short and sweet may be better - it has been for me.
kerpa
a/k/a Michael Miller
Chicago area

I'm doing lots now, both mentalism and cards. It is when the effect is new that I seem nervous. Sam the Bellhop is an effect that needs more patter than skill, a few different false cuts and flourishes that I can do in my sleep yet when I try and perform this, it goes horribly wrong! As you say, practice, practice, practice, I'll keep it going.

I suggest you practice in a mirror imagining you are in front of a large crowd. It will help soon to overcome fear.

Only confidence will overcome your fears.

I get the shakes too, but only right at first. Once the performance is in full swing they subside. I just make sure the first one or two effects I do aren't things that depend on finger-flinging. If you can find a pattern to them, you can work around them.