I did this a few days ago for easy skill ups, might be common sense. But let's face it, not a lot of people use common sense. Anywho.
Find a critter that runs away when you attack it. Not like the deeprun tram rats. I used the Sickly Gazelle in the Barrens, but anything will do. Try to find a place that's lower level than you though so you don't aggro mobs along the way and while you're doing the skill ups. Turn on Aspect of the Cheetah if you have it, if not then it's alright. It's not crucial. Fire Serpent Sting(Rank 1) at it. Notice that it's running away.
Run along side of the gazelle, not too close that you can't fire your shots, not too far away that you'll be unable to hit it. Follow it around firing Serpent Sting(Rank 1). If you keep shooting it rapidly, the DoT won't tick and you'll get a skill up. Just make sure to keep moving to keep up with the mob and to make sure autoshot never gets off, otherwise you have a dead critter. Then you'd have go look 50 yards away for a new one. Try to avoid the ranches with the baby boars and fences, because it's not as open and there's more opportunity to get too close to the mob and the dot would kill it.
The reason I used Serpent Sting(Rank 1) is because it barely costs anything mana wise.
Yeah, I know there are easier /afk guides on how to get weapon skill ups, but they're not all available to lowbies. I also checked to see if there was a thread like this, and I didn't see one. If it's a repost then it can be locked/deleted/obliderated off the face of the universe.