**This is NO repost whether you like it or not. I personally wrote every single detail of this guide, and I do not care if similar posts have been created. This is my own personal edition, and It is based on my knowledge and experiences. Thanks.**
I am talking of experience when I say that the Ambassador achievement can be hard if your character for example Isn't that old.
I recently started grinding for the achievement, and the fruit is quite nice I must say. First of all you get all those different mounts just by purchasing them for a little bit of gold from the vendors. These mounts are a good boost if you also want the 50 / 100 mounts achievement. Also, there's some pretty cool mounts between them all, for daily usage.
Anyways, the Guide:
First of all remember this: DO NOT consider buying or farming runecloth. It's a waste of time & cash.
Part 1/3 - Level 1-12 Areas
To start with, do all possible quests in the level 1-12 areas:
• Mulgore - Thunder Bluff Reputation
• Durotar - Orgrimmar & Darkspear Trolls Reputation
• Tirisfal Glades - Undercity Reputation
• Eversong Woods - Silvermoon City Reputation (NOTE: You will not be able to do the quests on Sunstrider Isle (level 1-6) unless you're a Blood Elf.)
These areas gives an approximate of 8k reputation for all quests. At this point the average character will be somewhere between 0-12k into Revered with most of the 5 factions.
Part 2/3 - Level 12-20 Areas
Now we'll move on to the next areas:
• The Barrens - Mainly Orgrimmar, Darkspear Trolls and Thunder Bluff Reputation. Undercity also has a few representants here.
• Silverpine Forest - Undercity Reputation
• Hellfire Peninsula: Falcon Watch - This one is for the Silvermoon City Reputation, since Azeroth lacks quests from this faction. It does of course require a higher level to do these quests, if you're not already 80. Although, you will still find several Silvermoon City questgivers added into Azeroth since 2.0.
I am not going to mention Ghostlands here, since It's almost pure Tranquillien Reputation your gaining in this area. I myself did only get 500 Silvermoon City Reputation by clearing the zone. Though if you want to boost your Exalted achievement series, It's an easy grind.
At this point you should be getting closer to being Exalted. Also, you've now done almost every quest there is to do pre- level 20. We'll move on to the last bit now, which is a bit less concrete though.
Part 3/3 - Level 20-30 Areas
• Hillsbrad Foothills - Mainly Undercity Reputation. You will gain side- Reputation with the other factions though. I got about 4.5k Reputation with the other factions here.
• Thousand Needles - Mainly Thunder Bluff Reputation. You will also see a bit side- Reputation here.
• Ashenvale - Orgrimmar Reputation, you will also gain a bit with Darkspear Trolls here. Also side- Reputation on some quests.
• Descolace - Mainly Darkspear Trolls Reputation. There's also several Thunder Bluff quests to find here.
At this point you should be at Exalted with all 5 Horde Factions. If you aren't, I highly recommend doing a couple of Alterac Valleys. Just loot all NPCs / Enemy players and turn in their Armor Scraps / Blood. Especially the Blood gives nice reputation with whatever factions you miss.
You will also experience that you will be much closer to being done with the Azeroth part of the Loremaster achievements at this point. So you basically just partly did 3 nice achievements at the same time!
That's all for now, I hope you enjoyed the read & find the guide useful.
If you have any questions, if find a typo or whatever, then feel free to comment and I'll answer you or edit asap!
Thanks for the feedback, I'll have similar posts soonish!