I've found the best way to level alts is Pet Battling over by Halfhill in Pandaria. My Nightborne Priest I got to 90 that way (the rest was WoD Treasures, then regular leveling post 100), my Mag'har Shaman I'm at 61 with 16 hours or so played. Having a second monitor to zone out and watch Netflix or whatever helps. I think it's the fastest way to get to 90 personally. I really dislike the leveling changes so I just Pet Battle now.
Skinning is a good money maker as throughout your travels you will fight many beasts. It also won't take much time, only 1-5 seconds after every beast. Miners and herbalists have to travel all the way to the nodes. Skinning also provides the passive bonus Master of Anatomy, increasing critical strike (which is especially helpful for agility-based characters who take it with Leatherworking).
I thought I was pretty clear? No? Here's what I do, simple really ... you have to quest to level 10 to get into bg's then 15 for dungies. Archy starts at 20. Get the pet addon that shows all the dailies for all continents - do these every day and not on some other toon because you get xp for the battle AND the turn-in. Farm archy as you come up to those areas while going to your next pet daily. Always, ALWAYS be q'd for dungies - level 15-60 will come sooooooooo fast. Rinse and repeat. Archy has the biggest xp gain of anything in the game for time effort. This is all I do, no elixirs, rest etc. I am finishing my panda priest right now and have a total of just under 4 days play time on him - that is only playing a couple hours here and there for a week or so. You can do it padawan :) You can also do level appropriate pet battles in the wild for xp but it isn't as good as the dailies unless you're in a high level zone.
Heirlooms are special pieces of armor that level up with your character, so they have stats that are always respectable for your character’s level (up to level 110). Heirlooms that fit the head, shoulder, chest, legs, and back armor slot offer an experience bonus. The total bonus is 45 percent if you have them all. It’s also possible to acquire a ring that adds another 5 percent, but you must win a fishing contest acquire it, and that can take some time.
But now, the Gear Advisor starts popping up, trying to get me to put the old 360 version Ring #1 into Ring #2's slot, since iLvl 360 is better than 350. Except I can't do that, because of the "Unique-equipped" modifier. So I click "Cancel". And then the window continues to pop up after every action my character takes, over and over and over, until I get rid of the old ring by vendoring, scrapping, or destroying it.