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First off, use this website for researching markets: Dulfy Level 80 Gear.
If you'd like to understand how to sell lots of items in Guild Wars 2, then you need to understand who is doing the buying. One common need within the Guild Wars 2 community is level 80 armor, and the six pieces that most people get when starting out is from the Trading Post. I personally grabbed a set of Traveler's gear for farming and Berserker's for PvE. This will cost you approximately 24 gold for each set.
So if you need high end gear to start farming fractals, your best bet is to simply break open the piggy bank. This also leaves an opportunity for people who craft these items to make a profit. Same goes for trinkets and weapons.
Unfortunately, a lot of the items you craft at the exotic level simply aren't profitable. But what often gets overlooked are the "rare" markets for crafting. Most of the exotic items you can create at a loss (like berserker's) have rare forms that you can craft for a profit. Just to avoid confusion, when I say "rare form" I mean yellow quality, not harder to find.
Guess what? There are plenty of people out there who cannot afford a few gold for their items, and also do not have the karma to buy starter gear. Their only choice is to fill out their characters with rares until they can afford exotics. You will make a killing by obtaining crafting materials with buy orders, crafting the gear, and finally selling your wares slowly over time. It's one more tool in your toolbox!
Surprisingly, most players ignore this "second best" market for armor and weapons. It's a shame really... there's plenty of gold in there for everyone.
One of the primary items used to craft exotic items has recently spiked in price... check it out here. I am investing in several thousand immediately and you should too.