all right, as a semi-veteran smoke I went through the same thing. Theres just a few simple things you have to realize:

Eye Drops (Visine/Clear Eyes/Whatever) is your best friend in public places.
The smell of marijuana smoke on clothes dissipates quickly, much faster than ciggs.
I've found if you just calm down and not think about everyone watching you (theyre most likely not) being high in public rules.

Also they most likely, don't care if you're high, I think you would be surprised that there are many other public stoners around you that you don't even notice