So you need gold fast to train stats or buy equipment? Be sure to read this first.

1) Leeroy Jenkins quest. To find this quest travel and click on “Vamprook Spyre”. A lot of talking but certainly worth it. This quest is recommended for all levels since you will face monsters depending on your level. The monsters are Light Vampragon, Fire Wyrm Dragon and Leeroy and Friends if you decide to steal their potions. For Light Vampragon use shining armor/avenger/canine warrior, sun shield/starblaze, any darkness weapon and truffle. For Fire Wyrm Dragon use fire plate/avenger/canine warrior and glave/starblaze/gyrate, any ice weapon(depending on your level) and ice vamp for guardians, while adventurers remain on truffle. Leeroy and Friends attack with 3 different elements, so glave/gyrate would be the best choice, as for a weapon choose the best one you have in your inventory. Truffle works best here. NOTE: this quest became guardian-only.
2) Knight Class. To find this class, go to Yulgar's Inn upstairs and speak to Blackhawke. I recommend this class especially for mages since they have 0 str and will have a hard time leveling up. The monsters here(axe knight, tank knight, black knight, green knight etc.) give good gold and most of them have a wind weakness so it’s good to use the level 4 ability from the dracomancer armor “Dragon’s wings”. Recommended for mid-levels.
3) Vampire vs Werewolf part 3. Recommended for all players since the monsters you face depend on your level. You will face Alpha Werewolf and Vampire Lord. Against Alpha Werewolf use wooden/glave/gyrate and a multi-hit armor. Low levels should get vamp or werewolf as quickly as they can since these armors are cheap and will help you a lot. Alpha Werewolf is weak against fire so use a fire weapon or spell(burn is good for low-levels) and fire vampragon. Vampire Lord attacks with dark and is weak against light and fire but weaker against light so use darkness shield/night shield and vamp(werewolf)/samurai form/canine warrior. Use a light weapon and light spell(low-levels should use daybreak or star forge if you are guardian). As a pet guardians should use light vamp/fairy god-mother and adventurers only have fuzzle which is a waste of money.
4) Ice yonder. Recommended for levels 70+ only. Because only then you will face the high gold monsters. Guardians should have no problem going to ice yonder(travel-crossroads-yonder-ice). For adventurers it is a little harder. First you need to go to Warlic’s magic shop and discover the combination for pet rock. Then go to Aria's pet shop, speak to Aria, choose “Visit Valencia” then choose “travel passes”. She will only let you go if you have the roc from Warlic’s shop. Then go to yonder ice. The monsters that give good gold are: centocor, krathan the centocor, the reaper, gogg, megogg, and avalurch. You can also face other monsters with lower rewards. Here are 2 VERY tough monsters: reaper and megogg. Reaper attacks with darkness and is weak to light. It’s attacks are very strong, but all of them are magic. So you should use dreamcather+daulfin rider(wizard robes upgraded to level 10 if you are guardian), a light weapon(hybee spear, nova/galaxy wand, orc cleaver or theiron’s spike etc.) and a good light spell: sunburst for adventurers and level 65 star forge for guardians. As a pet I recommend fairy god-mother(guardian-only) to heal your hp. Also have heal wounds just in case. Megogg is really hard, you will need nightmare plate+shield if you want to win. If you don’t have those a good replacement is invisibility cloak+gyrate. It’s better not to bother using any weapons(sorry warriors). Also don’t use heal wounds, the amount of damage he does is probably higher. He is weak against fire, light and darkness so you can use darkness dragon ambush(bag of bones, darksplatter), solar incinerator(fireball Z for guardians) or sunburst(star forge for guardians). Another way to beat megogg is to use the level 9 wizard ability, frostbite. It will stay frozen for 2 rounds, his fire resistance becoming 200%, and after that you can freeze him again until you kill him. NOTE: this quest became guardian-only.
5) Granemor cemetery. Guardians again should have no problem finding the cemetery. Travel then go to granemor. Adventurers again need the rock, speak to Aria, go to Valencia then go to granemor. The monsters you will be facing are mostly dark ones who are weak to light. You will also find BURP and demon panther which is weak to energy. This quest is good for exp only. NOTE: this quest became guardian-only.
6) Orc quest. Go to Yulgar's inn, talk to Robina and choose Special Quests-Fight Some Orcs. Most of the monsters here give good gold, and have no weakness. You will need glave/gyrate and invisible shield/dreamcatcher. Truffle is good too here. Choose whatever weapon you want. The orcs have weak attacks and spend most of their time regenerating life, so I recommend this quest for levels 30+ NOTE: this quest became guardian-only.
7) For guardians only, the special missions from the classes give very good gold and exp
8) Sailor Boon’s quest. Recommended for levels 70+. Guardians travel and go to Lolosia. Adventurers again get the roc, go to Aria's pet shop and visit Valencia and go to Lolosia. This is a tough quest, you will face many different types of monsters so I can’t give a good shield, armor and weapon suggestion. Anyway you are level 70+ and should have 1 weapon/spell for each element. At the end you get a chest with 4000 gold and 100 exp inside.
9) Kayda Reaver Quest. To access this quest go to Aria's pet shop, ask about valencia and choose Drakbots. You will face drakel opponents with low rewards except one: Drakbot. This monster is a little hard too, you need a good water weapon and spell. At the end of the quest you can buy 3 weapons too, but it’s the gold that matters. Drakbots will be pretty hard to find, so I won’t bother much with this quest since Drakbots are hard to find and there are better ways to get gold than this one. Do this if you got bored of farming the others. NOTE: this quest became guardian-only.
10) Guardian Arena. I’m not a guardian and don’t know much about the arena, but I do know that when you finish a stage you get a treasure chest. Also dragons revenge gives lots of gold and exp, and golems galore has the weapon golem which gives uber gold(credit to megasxx).
11) Zorbak's Hideout can be found on the travel map. You fight Calladus, and Drakath if you choose to pretend. They're pretty hard and there are lots of cutscenes which take long time, but the 2 monsters give lots of gold and exp
12) The uneasy peace. Go to the dracomancer class and choose "the uneasy peace between dracomancers and dragonslayers". Here you will fight lots of dragons. Don't continue the story, just click on "fight more dragons". I think this is better than the dragon revenge from guardian arena because here you can use dragon blade. Be careful, you might face Great Frost Wyrm and Giind. A nice way to farm the dragons is by using dragon blade and the level 9 necromancer ability, undead mutant.
13) The Bridge is another good place. Sail East to find it
14) carnax war scrollwhich you can find in the new town, Isle d'Oriens. Go into the library to find it. Those who are too low level to beat carnax can shoot him.
15) The Maze is also in Isle d'Oriens. Talk to Vince the Drakel for this quest. It may take some time for you to learn how to do it and it may be boring, but it gives 1000 exp and 1300 gold everytime you do it. After you do it 3 times you must re-login to get Vince's gold, otherwise you will get a treasure chest with 0 exp and 275 gold.
16) Epic Quest part 13 Nith gives very good gold and exp, although he has a high ammount of hit points and there is a little text too. Good farming place nevertheless.
17) Nightbane's Fortress Travel, go to Darkovia and do Nightbane's Fortress with the darklaw or a dragon blade. Recomended for levels 80+. When you get pretty far, don't click the "flee" button, just continue to fight.
That’s about it, I hope my suggestions will help you. Also all those good gold places give good exp too.