A few tips you should always remember when grinding:
1.: Always remember bandages and food, grinding is no good without it.
2.: Getting into big discussions/chats in the /gchat or /wchat or whatever is always fun, and it definitely makes the grinding less boring, however it will slow you down… You can go from 40k/hour to 30k/hour just by having a conversation in the chat which doesn’t seem to take up a lot of time… Keep that in mind if u really want to lvl fast.
3.: If you can’t stand to grind non-stop, just combine it with some questing to ease it up a little…
4.: If you go back to IF/Orgrimmar every half lvl to check AH, you will lose a lot of time with the travelling… Although u may have your hearthstone there, the trip back again will cost you a lot of time…
There’re many reasons to go back to the main city during your grinding, but I guarantee you most of them can be done with a lvl 1 char sitting in the main city, just to check the AH and buy stuff for you… You mail some gold to it to do your dirty work, and it can mail the items back to you.
5.: Always remember to sit your character at the nearest Inn when you log off, to gain rested time… It is really worth it, or rather: Not worth not to do it .
6.: I am very well aware of there’s some very good grinding spots in AV, however I highly discourage this, you will take up a spot in the battleground and you will not help ur team… You will actually help the opposing faction win, which is just stupid… Do not do this if you have any respect for your own faction!