Post by Nulgar
I'm assuming you're talking about Retail WoW, not Classic, since you don't mention that.
Edit: I just realized a very quick way, but I'm not sure at which level the portal unlocks, although
this comment suggests it's already available: Head to the main gate of Orgrimmar (south end) and enter the tunnel through it, but don't follow it to the right, instead turn left through a smaller gate, into the Portal Room of Orgrimmar. Don't go into the main room, immediately turn left again and go down the stairs, there you will find a portal to the Caverns of Time, which are in Tanaris. From there, ride north to reach Gadgetzan.
If you received a quest to go to Tanaris from the Warchief's Command Board, you should also have unlocked an appropriate flight point, likely Gadgetzan. Check at the nearest flight master whether you can fly there.
Here's a map showing where Gadgetzan is, to compare to the flight map.
If you want to go there for a profession quest, check the mentioned Warchief's Command Board (there are several in Orgrimmar) whether you receive the quest for Tanaris, and then take the flight point there.
If the above don't work or apply, well, there's the way on foot:
(optional: get the Inflatable Mount Shoes mount equipment from the Auction House, but these are likely still very overprized. Don't waste more than a handful of Gold on them)- First, take a flight point to get as close as possible.
- Assuming you start in Orgrimmar, leave through the main gate (south) and ride south to Razor Hill and then west (as in, following the road) or immediately head south-west, cutting through the countryside, but take care to stay north of the ravines in north-west Durotar.
- Once in the Northern Barrens, head south until you reach the Southern Barrens - there's a huge ravine separating the zones, but if you followed the road, you should find a way down and up again.
- Continue south until you reach this crossroad and turn east into Dustwallow Marsh.
- In Dustwallow, follow the road when it turns south, past the town of Mudsprocket and up into the mountains.
- Now, you are in the flooded Thousand Needles. If you have the Mount Shoes mentioned above, or are a Shaman with Water Walking (with does work while mounted) you can just ride over the large lake down south. If not, you can follow the mountains eastwards around the lake (be careful of Centaurs) and get up on the southern half of the mountainside ca. here (be careful of Pirates) and continue southwards to the pass into Tanaris.
- Finally, you're in Tanaris, and Gadgetzan is right in front of/below you.