I'm a fan of Throat Coat tea http://www.traditionalmedicinals.com/products/throat-coat/ (they do not pay me). It uses the same slippery elm bark as the drops mentioned earlier. I keep several bags in my calling box.

I think that I should try vocal warm-ups. What is hardest on my voice is having to run a beginner's workshop without a mic in a noisy hall. I'd rather run a shorter workshop and give the sound engineer an extra ten minutes to get the caller's mic set up for me to use, but this doesn't always seem to be possible.