Practice, practice, practice........that's about the only tip I can give you.
I'd suggest going in on your own time and familiarizing yourself with the POS
until you feel comfortable, especially since this seems to be your first
exposure to it. I've worked with just about every brand POS (Aloha, Micros,
etc, and even some home made versions) and once you get used to one, moving on
to others will be easy. The key is to get familiar with the locations of the
items, and there's really no trick to doing that - just practice! However,
typically, most modern POS systems (including Squirrel) are very intuitive,
and after a couple of days I'm sure it'll be easy for you.
Cheers!
Josh @ BarSim
www.barsim.com
BarSim - The ultimate bartending sim!