Returning player, what would you recommend?

Your classes would probably be rank 1, so it's probably best to rank them all up first to make combat easier, which you could do while completing storyline quests (which might be harder) or the best method, farming class ranks at the Legion Survival map or at the Underworld Arena. Other than that, I'd say completing daily quests for gold and level experience.

If you're leveling up, I'd recommend holding off on crafting any gear since crafting takes up a lot of time. You'd be best collecting drops... when you're level 25, the Blood Vampire Plate set is the best set to farm, and you can get the items from a drop from Lord Bludregen.

 

We now got class ranks so you should at least get classes that you use to rank 5 to get access to all base skills and it shouldn't take too long if you fight enemies close to your level or higher. If you get your class to rank 10, you get a cross skill that you can use with your all classes. I recommend getting Paladin, Dragonslayer, Warrior and Mage to rank 10 because those cross skills you get from them should cover everything you generally will be using.

To level up, you should do your dailies and do quests close to your level and so be sure to check areas with travel crystal in Battleon Town to see their level ranges.

As @Snowy said, you should go for the Blood Vampire Plate set when you reach lvl 25 because it's fairly fast set to get assuming that players are actually farming Lord Bludregen. You don't need to min-max your gear if you don't want to and just use dropped gear.