Realm First! Illustrious Miner

After picking up mining and herbalism in preparation to cash in on the new expansion. I started doing some research, trying to figure the best way to get ore quickly and efficiently for my guild's crafters. 
I. Pre-Cataclysm preparation

a) Mining enchant and mining helm

• +5 mining skill [Enchant Gloves - Advanced Mining]
• +5 mining skill(if you can wear mail) [Goblin Mining Helmet]

That totals +10 mining skill, and this is crucial advantage at start.
So if we merge those two things along with 460-475 mining, you can skip Mount Hyal or Vashj'ir, because that area will be so overcrowded with levelers and other miners, that there won't be possible to mine fast.

b) Ask friends for help
If you have a lot of money, you can ask few friends with mining profession, to mine Obsidium ore for you so you can smelt it. This is probably the fastest way to gain the achievement.

c) [optional] AH
This is the most expensive method. Ask your friends to buy Obsidium and Elementium ore while you mine, so you can hearth and smelt it and gain those last skills before 525. Count on this only if they can get a lot of ore in first half hour on AH(that's doubtful), because there will be first 525 miner in less than hour or faster.

II. Mining

A) 450-465 RISKY: Mining saronite ore(Wintegrasp) or Obsidium ore
Advantage of mining Saronite ore in Wintergrasp, that there will be no one there anymore. Rich saronite ore is still yellow and Saronite ore is green. Titanium is orange. Having a mage guildie or friend handy to help with portals will be useful. If you are mining in Wintegrasp, equip your enchanted gear after you gain 465 skill and head to Deepholm.

You can otherwise imediatelly go to Mount Hyal, and try to raise your skill to 465-470. Just go far away from quest starting zone, because of gankers(PvP servers) and questers.

B) 465+ (with enchants): Skip overcrowded areas like Mount Hyal or Vashj'ir! If you did what was written in chapter 1 of this guide, you can continue with leveling your mining in Deepholm while gathering Elementium ore.

As soon as your mining skill hits 475, start mining in Deepholm. Deepholm is literally loaded with Elementium wherever you go.

Have in mind, that adds are level 82-83. Advantage of jumping in Deepholm is that you avoid other people that will level or mine in Mount Hyal or Vashj'ir while questing.

Route for mining in Deepholm(source: almostgaming):

III. Conclusion - Quick what to do before/after Cataclysm release

• - BEFORE CATA: Enchant your hands and get mining head if possible for +10 mining skill
• - BEFORE CATA: Set your heartstone near Deepholm zone, so you can enter fast
• - CATA: Train Flight Master's License so you can fly in Eastern Kingdoms and Kalimdor.
• - CATA: Train Master riding(310% flying mount speed) if you don't have it already.
• - CATA: Go to Mount Hyal(Obsidium ore) or Wintergrasp(Saronite, Titanium) and gain skill of 465
• - CATA: Equip your enchanted mining gear and heartstone to location near Deepholm(AND/OR ask friends to send you Obsidium and Elementium ore) and good luck.