Leveling a Warlock is very easy in BFA if you have heirlooms. The main objective to do is gain as much experience as possible to reach level 120, but while you are at it leveling, questing and dungeons you can do something in particular while you wait for dungeon queues or battleground ones.
You can master two main professions I chose for my warlock Tailoring and Enchanting but you can get on a cloth class Tailoring and Inscription or Inscription and Enchanting or Jewelcrafting and Mining or Alchemy and Herbalism, you can combine any two professions but you have to take into consideration that some professions like Blacksmithing need mining in order to gather ore. Just like Leatherworking needs Skinning to skin beasts for their hides.
So I got Tailoring and Enchanting I think these two professions are the most common to mages, warlocks and priests I get these to whenever I make a new character and level up I also level my professions in parallel with my level I just think they are important and can be a viable source of gold if you sell the items in the auction house or something like that, you could just sell them to a vendor but it will give you a lot less gold than the auction house, many players need bags, for example, more than the NPC although the NPC cannot use bags you just sell the bag for him almost for nothing while bags in the auction house (depending on the slots) can get you 100 or more gold per bag. My point is with professions in World of Warcraft can be a very good source of income if you use them wisely. And with enough gold on your account, you can buy game time which is WoW Tokens.
I personally level while questing and doing dungeons , when I’m not questing I’m leveling my professions and doing dungeons because I made my character on a more lively populated realm than I was before I have my mains on Kazzak which I think is a dead realm because you wait in queue for dungeon finder and battlegrounds a lot of time and when I do PvP most of the time horde loses so I’m changing my realm on which I play but I’m not changing my faction (Horde for life) .
I got undead female warlock because I think it has very good passives for PvP and PvE, Shadow Resistance, Touch of the Grave, Will of the Forsaken are just one of them, because of the racial passives that go well with casters and looking good to me I got an undead female warlock with which I wanna go up to 120, and I think I’m going to do it in no time in this pace, in a few hours I got 30 levels so it was not hard.
The thing I’m wondering now is which Specialization to play I’ve played all three of them, Affliction, Demonology, and Destruction. I like affliction the best but while low level it can be hard to cast damage over time effects on every NPC in dungeons if you don’t have Seed of Corruption until level 38, and at level 60 the talent Sow of Seeds which casts 2 seeds of corruption on 2 different players or NPCs at the same time and because of this is quite hard to do some significant DPS with affliction while low level in dungeon, the best dungeons specialization I’d say it is for me Demonology, I always am in top in overall damage done with Demonology in dungeons.
It is easy and fast for me to level like this with heirlooms no matter what I do, questing, dungeons or battlegrounds I always get a lot of experience and Blizzard Entertainment just makes it easy for us to have as many characters as possible and try new classes and specializations throughout the game
I want to mention that when you do quests you have to be in the level zone of your expansion pack like Wotlk you quest in Northrend but you can stay from level 58 to 80 in Borean Tundra for example, when Wotlk was released the level range of Borean Tundra was like 68 to 73 (approximately) , now updated all zones from the Wrath of the Lich King expansion pack are 58 to 80, you can find the questing zone level rage putting your cursor over the continent you want to quest in, for example, The Barrens level range is 1-60. You just have to know the level range of each zone to benefit from each giving new content of questing.World of Warcraft 60 Day Pre-Paid Time Card – PC/Mac