stick with SM:Cath until L40, when you can wear mail. It'll help a touch with survivability.

Quest from L40-58 by following a guide. You can probably skip most collection quests without too much pain (I did). You may want to have someone run you through some key instances (like BRD) which have a TON of high-XP quests that you can complete.

58+ is outlands, and you'll continue to quest from there on out.

I'd ignore the disrespectful comments about paying people to run you through content. If you have the cash, go for it. I powerleveled myself through SM:Cath, but I'd certainly have paid someone gold to do that since it's so efficient. I would stop at L40, though. ZF and other instances aren't worth the trouble, in my opinion.