There is an event called Darkmoon Faire that appears in the game once a month, starting at 00:01 on the Sunday before the 1st Monday of each month. During the event you can complete quests for each professions.
The profession quests can only be completed once during each Darkmoon Faire and will grant 5 skill points (means you can complete them again once at the next faire).
The skillups will apply automatically to the most recent expansion profession progress that is not at its maximum. So, for example, if you want the +5 skill in Outland Engineering, but you have already learned other expansions profession skills, you have to max all of them out first, then you can get the +5 in Outland Engineering since that will be the only one that is not at its maximum.
Where is the Darkmoon Faire?
The location of the Faire is on Darkmoon Island. The portals to the Island can be accessed in the following locations:
You can find the portal to the Darkmoon Faire in Mulgore at the base of Thunder Bluff.
You can find the portal to the Darkmoon Faire on the south side of Goldshire in Elwynn Forest.
List of the quests
Some of the quest requires additional items, but all of those items can be bought from vendors, don't buy them from the Auction House.
The nearest vendors to the Darkmoon Faire portals are Shadi Mistrunner (Horde), Tharynn Bouden (Alliance). You can buy the Moonberry Juice for the Alchemy quest from Kuruk (Horde), Innkeeper Farley (Alliance).
- Alchemy - A Fizzy Fusion
- Archaeology - Fun for the Little Ones
- Blacksmithing - Baby Needs Two Pair of Shoes
- Cooking - Putting the Crunch in the Frog
- Enchanting - Putting Trash to Good Use
- Engineering - Talkin' Tonks
- Inscription - Writing the Future
- First aid - Putting the Carnies Back Together Again
- Fishing - Spoilin' for Salty Sea Dogs
- Herbalism - Herbs for Healing
- Jewelcrafting - Keeping the Faire Sparkling
- Leatherworking - Eyes on the Prizes
- Mining - Rearm, Reuse, Recycle
- Skinning - Tan My Hide
- Tailoring - Banners, Banners Everywhere!
I will mention it again, these quests can be completed every month, so if you are taking it slowly you can actually gain more than +5 skill points.