Trading - how do you do it?

To be honest, I have no idea how to trade in Guild Wars No, I don't mean the technical side, that is easy. But even though I played for some time, I have no idea what to sell/buy, for how much, whether I should just NPCs everything, or if there is something that is best sold for players for ridicilous amount of $$. Dunno, in other MMORPGs I played, it was fairly easy to notice general prices, so I had no problems with trading.

The fact that whenever I uncheck Trade chat I'm flooded with "WTS Godly Sword of Uberness" doesn't help, seems like hardly anyone buys anything. And what is worth buying anyway? Runes I can get from Rune Trades(except unIDed ones, but that's a big gamble), there's Dye and Material Trader.
I just can't find myself in GW "economy" I just NPC everything I find, few attempts to sell something ended in waste of time and I just NPCed those weapons anyway. (Maybe it's the color thingy? If it isn't gold, it must suck type of attitude )

Edit: Speaking of random crap I carry with me - do people actually buy any of those salvaged materials? I keep plenty with me for later use and to give them to guild members, but they seem so worthless and eat a lot of space

There's actually quite alot of things to cover and I doubt anybody can really compile a list because it's simple that others would flame it simply because of difference in opinions & willingness. When a same item can go from 1k up to 10k, there can be alot of people that are absolutely bent on the fact their way is correct, whether it be the desperate buyer who can only spare 1k, or the guy who knows he can trick people into paying 10x that. I can only give what information I have and am willing to share... so here it goes:

Regular Max Clean Weapons- 500 - 2,000
Unique Max Clean Weapons (Fissure/UW Weapons...)- 1,000 - 15,000
Regular +Dmg Mod Weapons- 2,000 - 20,000 (Note: This covers a very wide spectrums of effects, whether it be a +10% damage while hexed bow might go for only 2 grand, a sword with +15% while HP>50% might go for 20k.)
Unique +Dmg Mod Weapons- 20,000 - XXX,XXX (This is where it gets rather hazy, people can either be satisfied with 50,000 for a max dmg storm bow with +15% while blah blah, while some are demanding 200k+ while others are willing to pay it)

That's pretty much as general as I can get, collector items aren't really worth more than 2k, of course you can find buyers for more due to ignorance.

Salvaging items are only really good if you plan on keeping them in a bulk, if I had no tanned hide squares previously and I just got 7 of them, i'd rather sell it to the merchant if I was already low on space. The only real "money-making" materials would probably be steel. If you keep materials, either keep them to use/give away or just make some quick cash, if you're strapped for spaces, you can probably just sell them.

items with that mod are over 100k+, some are 500k+.