What am I doing wrong?

Today's ride was beautiful, very flat, and cut a bit short. Yet again, I am having trouble with the front derailleur. I decided to turn around when I couldn't get on the biggest or smallest front chainring. I was 'stuck' in the middle.

I'll try to adjust the cable myself this time, but this will be the fourth time it needs adjusting. (I took it in to the shop the other three times.) I've got to find out what's going on. Am I doing something wrong? Is it a bad cable? Is my bike not the quality I thought I was getting? I'm sure the LBS (local bike shop) will make it right if it's nothing I'm doing, but still.

The worst part was that as I was on the shallow part of an upcoming climb, I shifted (early, I thought) onto the smallest front chainring. Or, tried, rather. After refusing to go down, the chain went WAY down and jammed between the chainring and the frame. So, now the paint is pretty hurt down there. Well, who's going to notice except for me and any future potential buyers? I just hope it won't rust. Perhaps I need to look into some sort of sealant.

Anyway, enjoyable ride otherwise. Since it was pretty flat, I got to pretend that I could achieve a 15mph average with ease, spending quite a bit of time in the 18mph+ range on the flats. (I try not to get excited about descent speeds.)

Today's Ride: 15.08 miles in 1:00:51 (with a stop to fix the chain). Average speed: 14.9 mph. Total ascent: 695', total elevation gain from valley to peak: about 150'. (That's about as flat as routes come in Reno!)