The usual way to enter Westfall is by the road leading west from Goldshire. The first people you come upon will be the Jansens. They, like every other quest-giving NPC in this world, are in need of a little help. Farmer Fulbrow forgot his pocket watch at the pumpkin patch which is now overrun with hostile harvest watchers and defias smugglers & trappers. He gives you the quest The Forgotten Heirloom. To please go recover it from the cupboard in their farmhouse. The Fulbrow Pumpkin Patch consists of a field and a house just a little west up the road from the Jansen Stead - where you meet Farmer Fulbrow and his wife, Verna Fulbrow. It used to be possible to actually open the wardrobe from the west side of the house but that didn't work for me when I tried it just now.
If you're low level for the area (10 to 12) then you can try and set out on this quest right away. If you're up to it though, there are quests that require you to kill the level 14 Harvest Golems and level 12 Defias Smugglers that you'll find in and around the field and farmhouse. You can either fight your way through the field or head north from the road then west to get around the field. When you get to the house either kill the level 12 Defias and the level 15 guy inside or die trying. If you do die trying remember that you can rez inside the house and quickly open the wardrobe to get the watch. Use shift-right-click when you open it and you'll take the watch as soon as it's possible (autolooting).
There's also a small camp of 4-6 level 11 Gnolls nearby who can drop the Gnoll Paws that you need for the Patrolling Westfall quest. You can get this quest and many others at Sentinel Hill down the road, but first I'm going to finish up with the Fulbrows. Farmer Fulbrow also completes the quest Furlbrow's Deed if you found it over in Brackwell's Pumpkin patch (it starts with a random drop from one of the Defias there). Verna Fulbrow has two quests for you. One is the first part of Westfall Stew. This stage of the Westfall Stew quest just says to go to the Saldeen Farm and see Salma Saldean. To get there just follow the road south then turn right when you see a farm after the fork in the road. There are also signs on the posts and directions in the quest description.
Verna's other quest is Poor Old Blanchy. The reward for this is a 4 slot bag and a cloak. I do it for the XP of course. Old Blanchy is the horse behind them and Verna wants you to get her some oats. There are bags of oats around a lot of the farms and barns and even near some of the gnoll camps. This, like many other quests in Westfall, works well with other quests. I like Westfall for that reason, it's pretty easy to go in, pick up as many quests as you can, then go kill some things.
It's because of the shared needs of all the quests in Westfall that's I recommend getting the quests from the Fulbrows then heading over to the Saldeen Farm. After that go down to Sentinel Hill and get the other few quests you're eligible for. Near the tower at Sentinel Hill there's a gryphon point, a vendor and an inn with a mailbox. So you can set up shop there if you like for a couple days if you like.
After collecting up your quests, you'll need to kill a bunch of pretty much everything in Westfall. More specifically, from Salma Saldeen you've got Westfall Stew and Goretusk Liver Pie. The drops needed for these come from Murlocs, Young Goretusks, Fleshrippers, and Harvest Watchers among others. They're all over the place. Oh, and don't try going all the way back to Goldshire for Murlocs, the ones you need are on Longshore - that's the shore that runs along the north and west coast of Westfall.
Then there's Farmer Saldean's quest: The Killing Fields. That requires you to kill 15 Harvest Watchers. Note that there are others that look similar but the Harvest watchers are the level 14 or 15 ones. His field is full of them but there aren't 15 and it can take forever to try to do the entire quest right there. You're better off doing the ones in his field then heading back to Fulbrow's (after getting the quest for some Defias Smugglers at Sentinel Hill of course). Remember to look around Saldean's farm for the oats you need too. So pick up the quests at Saldean's place, kill some Harvest Watchers and head on down the road south to Sentinel Hill.
To find Sentinel Hill just follow the same road from Saldean's Farm for a little while and you'll see a tower on a hill to your right (west of the road). As you head towards it you should also see a gryphon master. This could be the first gryphon point you've ever come to so I'll walk through the process.
Thor is the Gryphon Master here. He's standing next to some gryphons. By talking to him, you can buy a ride on a gryphon. You can fly from any gryphon point to any other gryphon point you've ever been to. There's one in most of cities, often not far from the inn (there are also gryphon points in lots of places without inns). So the first time you talk to him you'll get a new flight path if you've ever been to another gryphon. If you talk to him but don't know any connected Gryphon points then you'll have to run back to Stormwind and meet the Gryphon master there before you can fly between the two points.
Now, at the tower on Sentinel Hill you'll find two fellows who have some work for you. They're Captain Danuvin and Gryan Stoutmantle. Danuvin has a quest called Patrolling Westfall. He wants 8 Gnoll Paws which you can get by killing (obviously) Gnolls. The Gnoll camps are found more to the middle and west side of Westfall but there is a camp of them just east of Fulbrow's Farm.
Stoutmantle has a series of quests, all called The People's Militia. The first one needs Defias Trappers and Defias Smugglers. These are the lowest level Defias that you'll find. Make sure to come back and turn in the quest to Stoutmantle as soon as you're done since he wants you to kill other Defias as well. You'll probably have to kill them for other reasons too so you may as well get those stages of the quests as soon as possible and get credit for them. A couple good spots for the Defias Smugglers and Trappers are near the Fulbrow and Saldean Farms. Good thing you waited to do those other quests, right? This is the essence of quest stacking.
The second stage of Stoutmantle's quest is for Defias Pillagers and Defias Looters. They can be found at the Gold Coast Quarry. It's directly west of Sentinel Hill then down a cliff. There are some more Trappers and Smugglers on your way over there (a camp just west of the tower). His last quest in the series needs Defias Highwaymans, Defias Pathstalkers and Defias Knuckledusters. These guys are in the footills in the south part of Westfall and some more on the way there.
Before you leave the tower the first time, Scout Gillian is by the lumber mill south of the tower at Sentinel Hill. His quest is Red Leather Bandanas. He wants 15 Red Leather Bandanas which drop from many of the Defias that you'll be killing for Gryan Stoutmantle's quest series.
That's not the end of questing in Westfall, but the rest of it basically amounts to getting out there and killing stuff. There are also a few more quest series that you can go on and a dungeon in the area, but I'm focusing on soloing and leveling here. I will say though that there are a few more good ones from Captain Sanders at the Lighthouse off the southwest shore of Westfall.