Here is what you SHOULD do to be able to queue using the Random Dungeon Finder Heroic as fast as possible with your main.
If you are starting in this server what you should do is:
You first have to decide which class you want to main, then, make an alt to learn the profession necessary to craft the armor type you will wear with your main.
Cloth / Leather - pick Tailoring
Mail / Plate - pick Blacksmithing.
With your main you should pick Mining / Skimming (depending on which profession you choose with your alt) and Jewelcrafting. The combination of Skimming + JC will make it hard to level up JC, so it up to you.
Then, give your alt the necessary items that you acquired with your main to craft you some armor to help the leveling process. Once your main hit level 78 - 80, you should have around profession level 425ish in your alt so he can learn to craft the level 78 set which can be learned from the NPC in Northrend.
Craft your level 78 set which each piece has ilevel 187.
With the JC profession on your main, craft you some rings, necklace and trinkets of ilevel 200. (the reason I told you to pick JC in your main is because the trinkets created from JC is bind on pickup. If you do not pick JC to craft your trinkets, you will either have to farm them from TOC runs with a group, farm FOS - POS to acquire enough Emblems of Triumph to purchase a trinket from Dalaran's NPC or purchase Darkmoon cards from AH, but the prices ranges from 1800 - 3000g each)
And for weapons you should do:
Knights of the Ebon Blade quest line and reach Revered Reputation with them, so you can buy from the NPC some ilevel 200 weapons. You should keep doing their dailies to reach maximum reputation to also be able buy their enchants.
There is also Sons of Hodir which can give you ilevel 200 weapons once you hit Revered Reputation with them and they also have enchants for your gear. So you should do BOTH quest lines here.
And there you have it, if you followed everything I said here your main should have:
A full set of ilevel 187;
Rings, Necklace and Trinkets of ilevel 200
Weapons of ilevel 200
You can buy a ilevel 200 cloak in the AH really cheap to reach 3k + GS.
Once all your slots have items of ilevel 187 + you should be able to queue for some Heroic Dungeon using the Random Dungeon Finder Heroic and from here gearing is very easy.
Good luck.