Hunters are perhaps the best characters for solo play, and that makes them especially good for leveling quickly. What is the fastest way to get to Level 70? Simply put, it is questing. Grinding will never get you the XP that quests will, especially since you need to kill things for quests a lot of the time anyway.
On top of that, quests give you new equipment and cash, which always come in handy.
The problem is, it is not always easy to know where you should be questing for which level, or which chains are appropriate for your level. Also, you have a maximum number of quests you can be on at any given time, so which ones are most efficient for your time? Which quests should be avoided altogether?
Once you have decided on the quests, you still need to get the info you need for locations for loot, mobs and turn ins, as well as any strategies you might need. Sure, you can look those up on Thottbot, but that is more time wasted.
For me, the best time saving was in getting a guide that already had all these things worked out for me. The most efficient path to Level 70 had already been worked out, and all I had to do was walk that path. And magically, every time I came to a new area, not only was I ready for the quests there, but I even often had quests to turn in right there!
There are many good guides available, but the one I used is still considered the "gold standard"for leveling guides, Brian's Guide for Alliance. Of course, as the name suggests, it is appropriate for Alliance characters only. Fortunately there is a sort of "companion" guide for Horde, called Joanna's Horde Guide. I am not sure if they are written by the same people, but this one gets equal praise from people that I know.
Both of these guides use the PDF format, often with links to quest info at Thottbot. They are quite complete, and are updated frequently for new patches. The only downside is the flipping back and forth between the game and the guide, but these is a very minor inconvenience.
This inconvenience has been eliminated in the iDemise Team guide. They have created a system of notes that you import into your game, and the map then contains all that you need for leveling: locations, tasks to complete, etc. I found this to be very convenient, especially since I could "highlight" the next location to go to, and simply run to the point on my mini-map. However, when I bought this particular guide it was very new, and there were a few mistakes, but they were easy enough to figure out in most cases. I expect that there will be updates as there is for the other guides. However, the one thing they don't have in the guide is links to Thottbot for quest info, so if you need to look something up you'll have to search for it.