Because fresh is coming soon, I'd like to share my warlock leveling guide (along with explanations WHY "this over this" aka don't listen to youtube plebs guides).
This one has been tested on current NW server (because different p-servers have different values of MANY THING [most important there are pet values]).
Build is affliction with some demonology talents over level 50" and it's focused on Draintanking", AoE pulls, Voidwalker tanking/sacrifice.
I'm explaining Voidwalker > Felguard and Succubus somwhere below.
This guide also includes spells skips, my current bind list and some "how to level" notes.
You will find there some shortcuts (like RoF = rain of fire, corr = corruption, immo - immolation etc.)
feel free to criticize.
1. Talent build
10-14 imp. corruption 5/5
15-17 suppression 3/5
18-19 imp. drain soul 2/2
20-21 imp. CoA 2/2
22-22 amp. curse 1/1
23-27 fel concentration 5/5
28-29 soul siphon 2/2
30-30 siphon life 1/1
31-32 shadow embrace 2/5
33-34 imp. life tap 2/2
35-39 shadow mastery 5/5
40-44 contagion 5/5
45-47 shadow embrace 2/5 -> 5/5
48-49 imp. corruption 2/3
50-50 unstable aff. 1/1
51-55 demonic embrace 5/5
56-58 imp. VW 3/3
59-60 fel int. 2/3
61-61 fel domination 1/1
62-64 demonic aegis 3/3
65-65 fel int. 2/3 -> 3/3
66-67 master summoner 2/2
68-68 imp. corruption 2/3 -> 3/3
69-70 kinda w/e, nightfall/imp. howl of terror/grim reach/CoExhaustion/fel stamina - all of those are more pvp focused
So, at 68 it looks like this https://tbcdb.com/talents/index.html?en&warlock&3502222510035105500010050330103200000000000000000000000000000000
Now some explanations:
Like said before... This build is focused on VW + draintanking + AoE pulls (by AoE I mean pulling mobs 1 by 1 in very short period of time) - this is explained below .
Because of that I'm skipping popular leveling talents like: nightfall, grim reach, curse of exhaustion, dark pact.
A) nightfall - it's simple, shadowbolt are close to 1/1 damage per mana. CoA is close to 4/1, corruption 2/1, immolate 2/1, unstable affliction 3/1, siphon life 1/1 but also heals you for that amount so you can say it's 2/1. So this is all about value, and once I hit mobs with dots I don't need bonus damage to down 'em (And If I do, I do it with drain life).
B) grim reach - because it's VW build, I simply pull mobs with VW to get first "10% of threat" + single torment. Also I can keep drinking (if needed) while pulling.
C) curse of exhaustion - kinda useless for pve, your pet + dots are strong enought to beat down elites (also most of em on NW are not immune to fear)
D) dark pact - with this build I'm trying to ALWAYS finish mob with drain soul rank 1, I also have improved life tap (btw. life tap doesn't breakes 5-sec mana rule), and VW's mana is too important to drain it.
And some other explanations:
A) 18-19 imp. drain soul 2/2 - I'm picking this at 18-19 because with ghostlands questing gear I'm regenerating around 130-150 mana per mob on this level (so this is already 3/1 mana value [drain soul rank 1 cost 55 mana])
B) 28-29 soul siphon 2/2 - at lvl 30 I get next rank of life drain, so picking this before concentration is kinda waste
C) 31-32 shadow embrace 2/5 - due to my calculations it stacks with soul siphon (this is finished at lvl 45-47 because damage boost talents are more important)
D) 33-34 imp. life tap 2/2 - there's no better moment to pick this talent (so I pick it just before shadow mastery is avaible)
E) 48-49 imp. corruption 2/3 - there's a lot of quests with spell damage items reward aroudn this level (before 40 I can get roughly 20 spell damage so this talent has low value)
F) 59-60 fel int. 2/3 - bonus for imp. drain soul (it's finished at lvl 65, there are more important talents ahead)
G) 66-67 master summoner 2/2 - because sacrificing VW is part of this build, summing it back 4 sec faster is save time
2. Playstyle and why I choose VW over Felguard/Succubus
I've been recently testing those 3 builds on NW ptr realm, and I found that:
A) There's no huge damage difference between VW and Succubus.
B) Felguard with demo build deals around 2x more damage than VW with same build (when he has frenzy stacks, otherwise damage is close to VW).
C) Dots are still main damage (even with demo build), so even with felguard dealing 2 times more damage than VW - it's still low (unstable affliction + siphon life deals more).
D) Leveling with felguard is slower because you can't do pulls AoE (you are missing siphon life) - You can pull like 2-3 mobs of your level and you end up fight with low hp/mana BUT [E]
E) with VW I'm able to pull 6-8 mobs with same level before I sacrifice VW, so I can kill up to 8 mobs in ~90 sec
F) warlock's pets are dying "super fast"
A) 1-10 - imp + dots, maybe some wand (there's nothing to do about it)
B) 10-29 - pull with VW + dots + imp. drain soul [finisher] + drainlife sometimes + wand sometimes (at those levels more likely I don't sacrifice VW but heal him with shadow consume shadows). W/o siphon life I'm not capable to pull more than 3-4 mobs (depends of mob level)
C) 30-70 - pull with VW + dots + imp. drain soul [finisher] + drain life + deathcoil + suffering + sacrifice (if needed. otherwise I just heal pet with consume shadows), so... because of siphon life I'm capable to pull more and more mobs at once (I'm care with caster mobs - they usually hit like a truck on p-servers)
I never start a pull with full HP - balance with life tap as much as possible for optimal value.
My itemization with this build looks like:
Spell power > Intellect > Stamina > nothing else (int over stamina because of imp. drain soul)
On NW you can abuse melee hit + wand (useful on low levels).
I Use necrosis addon to clear my bags of soul shards (from lvl 10 I usually have not more than 4 in my bags).
I only stack soul shards for solo-elite quests (curse of weakness + resummon abuse).
I have my own leveling guide (route), so In 99% of cases I don't fight mobs >3 level - so suppression 3/5 is enough.
3. Spell training and skips.
If there's STAR (shift+8 symbol) next to the level number - this means I skip visiting trainer at this level.
Also notice You can buy demon books pre-level.
There are some shortcuts - sorry, You will figure out.
4 corr / IMP-BLOODPACT
6 Tap / Shadowbolt
8 CoA / Fear / IMP-FIREBOLT
10 DS / HS / Armor / immo
12* funnel / Shadowbolt
14 corr / Drain life / You can Buy VW-SAC just now
16* Tap / breath / VW-SAC
18 SS / CoA / VW-CONSUME
20 Armor / funnel / immo / RoF / summon / Shadowbolt / VW-TORMENT
22 HS / Drain life / Eye
24 corr / sense demons / VW-SAC / VW-SUFFERING / You can buy VW-CONSUME just now
26* CoT / Detect invis / Tap / VW-CONSUME
28 banish / CoA / funnel / Shadowbolt
30 MOUNT60% / SS / Armor / Drain life / immo / VW-TORMENT / You can buy VW-SAC just now
32* Fear / WARD / VW-SAC
34 corr / HS / VW-CONSUME / You can buy VW-SUFFERING just now
36* spellstone R1 / funnel / Tap / Shadowbolt / VW-SUFFERING
38 CoA / Drain life / SiphonLife (Ratchet trainer may not have Drian life spell -> BUG)
40 SS / Armor / Howl / immo / VW-SAC / VW-TORMENT / You can buy VW-CONSUME just now
42* Coil / WARD / VW-CONSUME
44 corr / funnel / Shadowbolt
46 HS / Drain life / Tap
48 CoA / SiphonLife / banish / VW-SAC / VW-SUFFERING
50 SS / Coil / Armor / immo / CoT / VW-CONSUME / VW-TORMENT
52* funnel / Shadowbolt / WARD
54 corr / Drain life / Howl / You can buy VW-SAC just now
56* Fear / Tap / VW-SAC
58 SiphonLife / HS / CoA / Coil / VW-CONSUME
60 MOUNT100% / Unstable / corr / SS / DOOM / Armor / funnel / Shadowbolt / WARD / VW-TORMENT / VW-SUFFERING / immo
62 Drain life / Fel armor / You can buy VW-SAC and VW-SUFFERING just now
63 SiphonLife / VW-SUFFERING
65 corr / You can buy VW-CONUSME just now
66* VW-CONSUME / soulshatter
67 CoA / funnel
68* HS / Coil / Tap
69 Drain life / Fel armor / immo / Shadowbolt / VW-SUFFERING
Just a note about 100% mount - I don't do quest, I buy it for 595 gold (with revered rep.)
Also, at lvl 60 it's not kinda possible to gather that much money.
Clearing all quests in Hellfire Peninsula is worth around 250-300g (along with seling gray items) - same about Zangarmarsh.
I skip those spells during leveling (R stands for rank, the number inside [X] is level)
MOST OF DEMON BOOKS
CoWeakness R1  (till outlands - so I can abuse resummon sometimes)
CoRecklessness R1 
Searing pain R1  (this is great for pvp but I pick shadowbolt [becaise of shadow mastery talent])
Drain mana R1  (never found it usefull during leveling)
Drain Soul R2  (guess why)
firestone R1  - I wand sometimes (btw. this boosts pet damage)
hellfire R1  - I use RoF rank 1 to destealth druids/rogues if neccesary
Enslave R1  (most of demons you can enslave during leveling are not sripted - I mean "Their abilities")
CoElements R1 
RoF R2  - I only use rank 1 for some PvP
spellstone R2  - I only use rank 1 for dispelling myself from various mobs abilities
Soulfire R1 
incinerate R1 
Ritual of souls 
4. my leveling binds
a = alt
s = shift
c = control
4 unstable affliction
s3 target macro (Yea, I have few target macros for different leveling range - patroling mobs, btw. on NW there patrols are actually scripted A+)
s4 shadow bolt
s5 rain fo fire R1
a1 pet attack
a2 pet follow
a3 pet stop
a4 pet macro (totem killer)
a5 pet ability 3 (for VW it's consume shadows)
aQ pet ability 1 (for VW it's sacrifice)
E siphon life [A/D] / shadowburn [X]
sE death coil
aE pet ability 2 (for VW it's suffering)
R drain life
sR drain soul R1
sF howl of terror
G Racial 1
X amplify curse
sX targetself + bandages (on x2 [or higher] leveling rates I skip first aid - and fraische most likely gonna be x2)
aX fel domination
sC life tap
aC racial 2
V shadow ward
sV demon-fel armor
B necrosis menu
cA pet agressive
cS pet defensive
cD pet passive
5. one more note...
If you google "warlock tbc levelig guide" - most of them leads you to respec at level 50 to felguard build.
But I'm just a random pleb, don't listen to me. Or am I? - .-