Mining and skinning. When you hit level cap, drop skinning and pick up engineering. Use your mining in Dire Maul East jump runs to make a bunch of gold. When you’re satisfied with your reserve, switch to tailoring.
Go enchanting and herb for dat gold making
Idk much about blacksmithing or leatherworking. I do think LWing has a CD they can use for profit.
Tailoring- You get the bop epic chestpiece crafted at lv60 OR bloodvine set which is even more important for a warlock to get since locks have less hit than mages from talents. Also at like lv35 you can make a Robe of Power BoP spellpower robe, oh boy…
Mining- A weaker gold per hour gathering prof. A real pain to level 65-125 in your 20s to reach iron and the ores arent that valuable (least on my server)
Stones are decent money, Coarse stone and up is 2g a stack on my server. but the ore is only 1s for copper and tin, iron is like 5-10s, mithril 10-20s, thorium 10-30s.
Herbing- Herbing beats mining because
briarthorn 1g+ per stack AND a chance to get
Swiftthistle 4g+ per stack, a solid 20-25s per piece item. getting x3 from a single node is like getting 75 copper ore by comparison.
Wild Steelbloom 10g+ per stack, yup these are like 40-80s each. finding a single node of this is like getting 40-1.2g guaranteed gold.
Purple lotus 1g+ per stack, also drops wildvine worth 1g each
Firebloom 15s-20s each, great investment herb for phase 5 when more mages go fire and use fire power elixirs
As you can see herbing outsells mining at every level bracket. Minings only saving grace is the rich thorium nodes having a tiny chance to give you an Arcane Crystal worth 60g+. But thorium nodes are so rare to find and the odds are so little for crystals you would have a hard time farming 1+ crystals per hour unless you did jump runs in Diremaul.
Alchemy has the transmute CD you can unlock at 35 for that juicy 5-7g profit every 2 days… not too big but yeah its extra gold. You also get to craft your own pots and elixirs and get things at the lowest price possible. Alchemy is kind of bad though because you can’t make your own mana pots, flask or 35 spellpower elixir without major time investment and gold getting these recipes. I’m talking the major mana pots lv60s use which is a BoP drop from scholo i think.
You can do other fun things like invest in fire oil for phase 5 or make free action pots so you can 1 pull sm cath on a mage.
Skinning is kind of bad in the early stages.
Light leather- vender it
Medium leather - vender it
heavy leather- vender it, 2s on AH is too low, if you dont sell the deposit fee takes away all the profit you were trying to get and trying again comes at a loss.
Thick leather is the first leather that is worth selling which happens in your early 40s.
Rugged leather would be good but ZG tanked the price big time.
Skinners can also skin rare scales from Ubrs and Onyxia if you got a skinning knife with max skinning.
Engineering is amazing if you max it as much as possible as you level and enjoy the benefits of
1- engineering hats even at lv15
2- Bombs that hit like a truck and are aoe on a 1min CD, enjoy pulling 3-4-5 mobs together and bombing them. at lv10 using course bombs on my warrior let me aoe grind packs of 5 harvest golems. the bomb would chunk 60% of each mobs hp effectively getting me 2.5 kills worth of damage.
3- Target dummy lets you farm fused wiring which is 3g each AND the dummy taunts mobs causing you to take less damage or in some cases lets you taunt off mobs so you can bandage up. the mats per dummy are only 10s but the dummy has like a 20% chance of dropping a fused wiring worth 3 gold. so 50s on average gets me a 3g item. means every 10 minutes i turn 50s into 3g while casually leveling and using dummies on CD.
Fused wiring is used to make repair bots in case you were wondering why it had its 3g value. On some servers its probably 5g+
Good answer. Swiftthistle is actually worth about 75s PER on my server right now. Please nobody else on Kromcrush start farming swiftthistle until I finish leveling 
crafting profession on leveling is waste of space. Go one gathering + skinning for max gold.
For PVE you’d also want to be a tailor at 60 in this phase, cause bloodvine
Do warlocks who have eng have any issues or find it annoying with dots breaking bomb stuns early? I know dots aren’t exclusive to warlock and bombs aren’t the only thing eng offers, this is my inexperience with using the profession showing lol
Think of the bombs as an interrupt on your warlock…