Mostly I read a ton of buyer reviews when I'm in the market for any new electronics - doesn't matter what it is, it could be a computer, a stereo, speakers or else a USB hub or etc. Basically, if it has a good ratio of good reviews to the few bad ones (mostly from idiots who didn't fully read the product description to know exactly what they were buying), or no bad reviews at all, then I put it on my "to be considered" list and then I proceed off of that to check out and compare the specifications and the prices.
For me, the biggest factor is the price vs. value ratio. What I mean by that is because I make so little money because I'm only a seasonal hire (really bad job market out here) I buy the cheapest one with the best features in that price-range I'm looking for, and which has the most good reviews. I also look for videos to get an even better idea of what it's actually like - YouTube is superb for that.
Anyway, when I bought my 23" Samsung SyncMaster I was looking for a display that would allow me to combine my monitor and a TV, which had at the very least 1 HDMI port and external audio capability with a very good response time on it (everything else was a bonus, such as the VESA mount support which I will be utilizing at some point by tossing it onto a wall-mounted monitor arm). I knew I'd pay a little more for all of that, instead of being able to get a nice 30" standard WS monitor without the TV tuner for less than what I paid for this one ($249 - could have got the 27" for $350 but couldn't justify $100 extra for the extra 4" of screen).
Basically, just keep your eye on the reviews. They are the best way to weed out shoddy products and ensure a good outcome.
Edit: Just a little side-note. My 23" has a dynamic contrast ratio of 50,000:1 and which I find more than sufficient for my needs on both the HDMI as a display and over the TV feed (it is GREAT with gaming too). We have a big 60"+ Samsung in the living room with a HUGE contrast ratio and I see absolutely NO difference between my 23" and that one at all. So don't focus on that too much, and you could save a good portion of your money by going with a 50,000:1 or a little higher. IMO, you DON'T need to go over 1,000,000:1 etc. for a PC display and this goes for the ones with a TV tuner as well. It won't boost anything very much at all. The main focus is the HD, if it's 720 or 1080 (mine is both - I get the full 1080 as a monitor, and the 720 as a TV - but that's only because we don't have HDTV service) and then the response time. Just thought I'd chime in on that.