1st: If you delete a character, you can’t reuse the name. It’s gone. Probably forever.
They don’t have a way to release names so they can be reused and don’t plan on implementing one, which means names will have to be manually released by customer service, something we shouldn’t count on being able to ask them to do.
Edit: They have changed this. Characters level 10 and below that are deleted, their name will become available immediately. Characters 11 and over that are deleted will have a 60 day cooldown before the name is available again.
Healing potions: You need to use lots of healing potions in this game and there are two types: amount healed and percentage healed. The ones that heal a percentage of your health are the only ones usable in raids. They are extremely valuable. Don’t use them while leveling or outside of raids.
Pets: All pets pick up your loot for you. Use one.
Open world trash mobs - Don’t bother killing open world trash mobs that you don’t have to. They give almost no XP. Most XP comes from completing quests.