You don't have to mix them. In the past I have used alcohol alone to help with public speaking.

It doesn't take much for me, 1-1.5 beers is all it takes to stop the jitters if I have an under-prepared presentation to give. Not enough to even call tipsy (best to avoid that, for obvious reasons).

Isn't that how everyone prepares to give a presentation? I thought it was standard operating procedure.