When I started riding my first adult bike, I counted the teeth on each chainring and each rear sprocket, then made up a tiny three-columned chart (handwritten--it was the early 80s and I had never even used a computer), then taped it to my handlebar stem. Does the term "geek" come to mind here? Anyway, that helped me get used to what was where, and since I had downtube shifters, I was able eventually to get a feel for which position meant which gear and, thank goodness, get rid of the little chart.

Fast-forward to the 21st century. Now I have barend shifters, but I'm pretty much operating on feel, in the sense described by Spokewench and Lisa. I use the middle chainring for most flat riding and not-too-aggressive ups and downs, move down to the smallest chainring when the hills get too steep, and reach for the largest one when I'm flying downhill and want to keep spinning as long as possible to take advantage of that hill. Then I use the rear gears for fine-tuning, avoiding the crossover thing as much as possible, of course.

This works pretty well for me. I still do an ungraceful move sometimes when I'm reaching for an easier gear, but in general, I'm reasonably smooth for someone using barcons. And no more geeky little chart!