Ok, This is how I get to level 70 in about two weeks or so.
1-12
Starting Area to Next Town.
12-20
Go to Westfall and kill level 12s and 15s until your level 17 then find a group for Deadmines.
20-30
Go to Duskwood and kill undeads near the left side when you enter.
30-43
Go to STV and Kill from top to bottom, Then kill the pirates until your level 40 or so.
43-51
From level 43 and up go to Gadgetzan and kill from the edge of Tanaris near Un'Goro.
51-56
Go to Un'Goro and go up threw Un'Goro until you reach the gorillas at the top.
56-60
Go to Silithus and kill the Wasp looking things until level 60 then hearth back.
60-70
Once level 60 go to Shattrah City, Become an Aldor or scryier by doing so you can get easy EXP by doing the quests Khadar gives you. Once you've done the quests go out to Terokker and go north until you find these Old Fashion looking Draenei. Kill them and also get the Netherweave and Runecloth because it sells for alot on Auction House for about 20g or so. once your like level 65-66 go to Shadowmoon Valley. Until your level 70.
I hope this helps ! If it has please +Rep.