For 50+, Weeping Coast is highly recommended but if you find things a bit tough there, you could always drop back to Ravenfell which is 45-50 and might be a bit easier for you.
After Weeping Coast, you'll be moving through to Savage Lands and then to Aotulia Volcano. Ask someone for a quick guide on how to reach Dimarka when you first enter AV - there's a load of elite Naga just waiting to relieve you of your hp.
At level 54, Mysterious Torrog in Dimarka will offer you a quest for travelling to Thunderhoof Hills. Questing there is a little difficult at 54, but still possible. You need to be careful of the debuff from the Chupura's & the Cockroaches.
There is a nice level 55 armor set to pick up in Thunderhoof Hills and the zones progress one after another from there so don't worry about which zone you should be in as they work sequentially.
I'd recommend Weeping Coast (remember to pick up the hidden Epic chain too) followed by Savage Lands. Stay in Savage Lands for as long as you can and move to Thunderhoof Hills at 55 to pick up the armor package before you start questing there - makes it a fair bit easier.
Good luck!