Unless you're starting out from scratch, in which case you might as well pick up everything and vendor it, then there's a great deal of rares (not to mention blues) that you can safely ignore and not waste inventory space or identifying time on altogether. For example, while you can ignore rare two-handers (since the legendary Skorn blows them out of the water 9 times out of ten), you should always be picking up rings and amulets. I typically pick up gloves, wrists, shoulders and 1h weapons too, as long as they've got an ilvl above 60. Some of those might be a waste of effort along with two-handers, but I've gotten lucky a few times with those slots, so I've stuck to looting them.
When it comes to pricetagging your stuff, there are two things to take into consideration from the get go; 1) take a moment to right-click and quickly browse the estimated value of items with similar stats already on the AH, 2) if it's a so-called 'Trifecta' or 'Quadfecta', meaning it's got 3-4 of the highly coveted rolls (mainstat, +critical hit chance, +critical hit damage, +attack speed), then you're pretty much set. For example, the difference in price between a ring or an amulet having two or three of the aforementioned rolls can be measured in by millions in double or even tripple digits, at least on the European region AH. Simply put, if you've got a trifecta item or better, then it's worth something to someone.
Unless you're trying to move something like that, or one of the highly sought after legendaries with a half-decent roll like a Mempo, Echoing Fury or Witching Hour etc., chances are your auction won't sell until you put it on a firesale, that's been my experience with the European AH these past 3-4 weeks at least. The market is beyond FUBAR with some players wielding market dictating bankrolls and a lot of douches thinking they've hit a jackpot just because they scored some above average item, both making for a less than stellar experience for the average Joe who just wants to sell off some stuff and put gold towards some future upgrade. When you try to sell your stuff, figure out for yourself if you've got the patience to fish for the right buyer to come along or just need to move the item as fast as possible, and then price accordingly. For example, I recently picked up an amulet (STR, VIT, CritChance, CritDam and some junk rolls) which I determined to be in the 100m range taking the availability and price of similar items on the AH; I started with a buyout price of 125m, but after a couple of days of relisting after it didn't sell, usually shaving off about 5 million each time, it finally sold overnight at the buyout of 110m. It would probably have moved faster if I had started out below 100m, but since I wasn't in any immediate need of cashflow, it paid off to relist a few times.
Finally, you can take a look at the gear that the highest ranked players are using, to form somewhat of an idea of what's end-game, ie. check out diabloheroes.com or diabloprogress.com - furthermore, I recommend checking out diablofans.com for rough pricechecks and other information, which might be valuable for you since - per your post - you've been out of the game for some time. If all else fails, post a screenshot of your item in this thread, and I'm sure you'll end up with some suggestions.
Hope that helps some!