Playing as many instruments as you have friends who'll allow it is posibly better even than going to merchants. You'll have at least a fair idea of how well instuments your friends are using are set up.

Although you're unlikely to find it at reputable dealers, if visiting a second-tier seller (esp. used instruments and pawn shop types) it's a very good idea to take a tuner and do at least a rough check of the absolute tuning. A favorite trick in the pawn shop and similar businesses is to "tune down" (I've found at least 5 semitones variance) so that the action feels very light, but when you get it home and tune traditionally you're playing a two-by-four with aircraft cable for strings - or so it seems. They can rely, usually, on ambient noise to cover the absence of "voice" at the slack tunings.

For a beginner, it's probably more important to get an instrument that "feels good" than one that "might sound better when you learn how." The choices of the expert players often are based on "loudness," "projection," and other arcane things you're not likely to wring out of the instrument at the beginning stages - so just sort of ignore them, at least until they explain (and convince you that they actually know) why they like their particular instrument.

I have one $150 plywood Chinese factory mando that's one of my favorite ones to play, and that compares quite favorably with my $--- Washburn. I have a $1700 F-style that I never play (of a brand mentioned above) because I don't need "that loud" and it's a lot harder to play aggressively enough to use what it does best (plays loud and ...).

John