The advice here is only gudlins to the game, and only my way to go.
Remember it is always easier and quicker to levle if you are having fun.

1-80 level

Find a buddy and level with him/her.

Run tank or healer, atleast one of you should chose this option.

Buy levling gear and weapons and enchant them. (If you have a level 80)

Send 50gold and bags for the new person (if you have a level 80)

Do not take only one quest at a time but gather as many as you can.

Run battleground at 17-19, 27-29, 37-39 .... and so on

Remember rested xp (but only from level 25 and up)

Remember instance quests (due to new instance system)

That is our advice.
Best Regards.
The G.o.N. Crew!