Daily Challenge & Purple Train

Completing Daily Challenge gives you good rewards! It is recommended to do it everyday!
You can choose either of the 3 Daily Quest to complete your Daily challenge to get stuff like Materials and Golds.

And why stop there?
Do all the Daily Quest!
There is a term called "The Purple Train" which is to do all the purple dungeon in a row. Either from bottom or from top! Its your preference :D It starts at "Lair of the Frozen Fang" and ends at Hollow's Heart currently. All the quest available can be found right outside the gate in F8.
The harder the dungeon, the better the gold! 

Truth be told, some dungeons are hated and are hardly or even never done by players... Gloomdross Incursion and Awakened Necropolis are pretty boring to do so people hardly does them...
And the legendary Sunder Nexus which somehow is excluded from Daily Challenge with not much decent loots, I don't see anyone ever asking to run this dungeon before.

Heaven's Mandate and Cold Storage are once a day only dungeon. You will get locked out after killing the boss, so remember to take the quest before going in! Heaven Mandate requires a White Orb to start the boss while Cold Storage requires the white orb only for the 2nd boss. Most people just do the first boss.
They also give 1 treasure pouch for everyone + one drop for bidding.
MOML means My Orb My Loot, its a courtesy that you do not bid on the loot as the loot of for the person who use the White Orb. This is because the White Orb is rare and they are sacrificing theirs to help you complete the quest.
Please respect this community rule, because if everyone doesn't follow it, no one will use their orb anymore and those without orb will have a hard time.


Event
You should also check out what's the current event as there will always be an event going on.
From my experience, most event comes in a form of token/currency to exchange for very good items in Dragon Express.
Of course the event varies, for example there was one event which requires you to craft instead.
So check it out because they often really give very good item.