1. Go to a dungeon.
2. Kill everyone, and loot what you can.
3. Sell everything.
4. Repeat

All I wanted to say was already written by Mr. Verranis. Actually, that's all.
But when you pick up items, as the slot of bag is limited, you should choice two-hand weapons and you can sell it at better prices.

I do not know if this is allowed but apparently there is a quest that give you a mount as a reward :p......

Well. i guess you can just speedhack, speeds up the processs u know, i'm betting thats what alot of players do.

Verrantis speaks Veritable Words of Wisdom, here is a verbose version:

1) Find an area with some creatures which you can kill comfortably, preferably a dungeon, ideally close to a gate. As you progress try to change this area to tougher mobs.
2) Kill the creatures and if you find your bag overflows prioritise weapons (2-H even better) then torso armour.
3) Exit to the title screen and log back in - this will get you to the area capital where you can unload keepsakes into the bank and sell the rest.
4) Port back to the gate near the killing zone and repeat.

Hello,

I do exactly the same as "Me".

Also do the scarab cave quest, more bag space man!

My method. Continental highlands. Go to Raptor Caverns located at E2 on map.
1. Pick up everything in cave, borokful tears, ghost fungus, and raptor eggs!

2. Fill bag, leave and run up side of hill left of cave entrance and go to G2 to sell items, run back up hill and re enter caves.

3. Eggs stack at max of 40. So if you reach 20+ in your run, make sure to put them in the bank. Check egg nests on the way to cave as well.

4. Once you've gotten some money from selling gear, craft all of your ghost fungus and raptor eggs into the lowest craft possible until you're out. A 6 stack of crafted eggs sell for 528, so the eggs being picked up is a must for faster money. The fungus crafted won't yield as much but it's a little extra. You can either keep the tears for crafting or sell them for a little bit of gold.

You can make any where from 2-4k a run just selling gear you find and even more if you craft the items you pick up like I said.

This was run with a BLADES skill build. Bladestorm and another AOE are a must for a nice clean run in under 30 minutes. You will automatically have wheelstorm on the way to getting bladestorm, but one point in SWIPE can also be nice.

Hope it helps!

I forgot to mention. Save all JAGGY TEETH and ONYX STONES found in cavern. Onyx stones stack at 20 max so you know! But when you have a good amount of each. There are two repeatable quests at G2. I believe it is 5 onyx stones give a glittering metal dust and 150 experience points. 4 jaggy teeth give 80 xp and a sharp tooh. You can sell or keep the dust and sharp teeth for crafting.