Hit Dice: d8 is middle of the road. You’re going to be primarily focused on ranged damage, and will need to watch your engagement radius so you don’t get mobbed.
Weapon Proficiencies: Simple weapons mean you have few options in combat.
Armor Proficiencies: Light armor isn’t much, but if you’ve got a good Dexterity you can make it work.
Tool Proficiencies: None.
Saving Throws: Charisma saves rarely come up.
Pact Magic: Warlocks have a very useful spellcasting style. They only get a small number of spell slots, but hey recover after a short rest. This is just enough to use a buff or debuff at the beginning of combat, and still have use of one or two more utility casts before they’re tapped out. However, having access to the best cantrip in the game in the form of Eldritch Blast and all its modifications means there’s little temptation to spend your action doing anything else.
Pact Boon: There are several options available for your pact boon, and they shape your character as much as your choice of invocations or Otherworldy Patron.
Pact of the Blade: Melee warlock is a tough build. You have a very straight path to follow or you risk being entirely outclassed by a normal melee character. The perk is you get access to lots of magic weapon abilities early and reliably, while your other fighter friends will have to work for and pay for their magic weapons.
Pact of the Chain: Having a familiar is very useful. You can use it o scout, flank, and send messages. With the support of some invocations, the familiar you gain can become a powerful ally that will greatly enhance your abilities in combat.
Pact of the TalismanTCoE: A talisman imbued with your magic, which you can further enhance with invocations. The best part of this is that you can hand it off to another character to use if you need to.
Pact of the Tome: Overall, the best option. You gain a bunch of spellcasting options that really show off your caster abilities.
Mystic Arcanum: You get your best spells through this ability. They don’t use your spell slots, so this is a huge bonus.
Eldritch Master: A very mediocre and mostly useless ability for a capstone class ability. The best this can offer is the ability to multiclass without missing anything too important at the end.
This is your main character-building feature. choosing invocations that work well with your play style, party responsibility, and are named Agonizing Blast, are very important.
Agonizing Blast: This is the single best and most important class ability of Warlocks. If you don’t ake this, and work on maximizing your Charisma as early as possible, you might as well just play a different class. Not taking Agonizing Blast is a handicap you simply cannot overcome.
Armor of Shadows: Mage armor is only +1 better than Studded leather. If you’re going to get medium armor, this is obsolete. Otherwise, there are better offensive and support options for you.
Beast Speech: You don’t need this.
Beguiling Influence: You’re going to pick deception and persuasion from your class/background allotment of skills anyway.
Devil’s Sight: Ignoring one of the most common environmental and arcane hazards, darkness, gives you a tactical advantage few can match. If you learn to cast darkness yourself, you’ll have a very powerful (if selfish) tactic to employ.
Eldritch MindTCoE: Your most commonly used spell, Hex, requires concentration. Why let it fall for no reason?
Eldritch Sight: It’s faster than casting detect magic as a ritual,
Eldritch Spear: The base range on Eldritch Blast is usually good enough.
Eyes of the Rune Keeper: This one is soft. You can get a couple of languages from your background. If you need more, it will be situational and you can always hire a translator or find someone to cast comprehend languages or tongues.
Fiendish Vigor: Good duration, no limit on how many times you cast it, and a decent duration makes this a great invocation for heavy use.
Gaze of Two Minds: Situational, and not terribly strong.
Grasp of HadarXGtE: Repelling blast fits better with the squishy nature of Warlocks.
Lance of LethargyXGtE: Not terribly useful or powerful.
Mask of Many FacesPHB: Quick shapeshifting, which is typically only useful if you’re an infiltrator.
Misty Visions: Better than minor illusion, but still not that great.
Repelling Blast: This can be used to break a grapple, get someone out of melee engagement, knock a creature off a cliff, through a door, or many other things.
Thief of Five Fates: Not worth the spell slot.
3rd Level Invocations
Aspect of the MoonXGtE: If you want this, play an elf.
Book of Ancient Secrets: This is much better than taking the Ritual Caster feat, or many of the other invocations that give you ritual spells.
Gift of the Ever-Living OnesXGtE: Hopefully you aren’t stuck in the position to need this, but if you find yourself doing a lot of healing, it’s worth it.
Improved Pact WeaponXGtE: Hopefully you’re going to have a magic weapon to use instead of this invocation, but this might give you a bonus early. It really depends on your DM and how often you get magic weapons.
Investment of the Chain MasterTCoE: If you have a familiar, this is mandatory. You go from having a pet that you can use for recon to having a combat-ready ally.
Rebuke of the TalismanTCoE: Outside of hellish rebuke, you don’t typically have anything to do with your reaction, so this is worthwhile solely on the action economy it provides.
Voice of the Chain Master: Investment of the Chain Master is strictly better, but his is a solid addition once you’ve got that. It allows you to scout more effectively, and communicate with people at a distance.
5th Level Invocations
Cloak of FliesXGtE: Strictly for Hexblades who find themselves in melee frequently, this has the potential to cause quite a bit of chaos. It lasts until dismissed, so once it’s on you can make good use of it later.
Eldritch SmiteXGtE: Considering the damage eldritch blast with hex does, this isn’t worth a spell slot.
Far ScribeTCoE: Sending, message, or a cheap magic item can mimic this, which will usually be used for plot reasons.
Gift of the DepthsXGtE: Definitely a must in an aquatic campaign, though you’ll probably have a reliable way to work underwater before you get to 5th level.
Maddening HexXGtE: You’re likely going to have Hex up all day long anyway, so you might as well make the most of it.
Mire the Mind: You’re likely to have better uses of your spell slots.
One with Shadows: Invisibility is great, but the conditions on this aren’t conducive to the things you’d likely be trying to accomplish while invisible in the first place.
Sign of Ill Omen: A very poor use of your spell slots, especially at this level, and even worse as you advance.
Thirsting Blade: Hexblades need this mor than any other invocation. The only way for your pact weapon to keep up on damage is tog et more attacks with it.
Tomb of LevistusXGtE: This is your panic room. You’re likely to use it as a last-ditch effort, so it’s not the best thing to have. Plan to never get to the point of needing it.
Undying ServitudeTCoE: It’s on theme, but just underwhelming. Ask your DM to house-rule summon undead or the like to the Warlock spell list.
7th Level Invocations
Bewitching Whispers: As great as this is, it really doesn’t scale well as you increase the level of your spell slots.
Dreadful Word: Confusion is an unreliable debuff. Skip it.
Ghostly GazeXGtE: One of the better overall invocations, this allows you to never be ambushed on the other side of a dungeon door.
Protection of the TalismanTCoE: The Pact of the Talisman gives you access to a strong ability here. Considering you’re a very frail class, having more protection options is always a good thing.
Relentless HexXGtE: Sometimes you need extra movement, but given your capacity for ranged attacks in eldritch blast these occasions are few and far in-between.
Trickster’s EscapeXGtE: Freedom of movement is a powerful spell, but you’re not going to need it ninety-nine percent of the time.
Sculptor of Flesh: polymorph is one of the best buff spells in the game. Transforming a frail spellcaster into a powerful creature can save their life, and provide another melee ally right when you need it. Disguising a character as an animal allows a strong infiltration tool.
9th level invocations
Ascendant Step: You can cast fly.
Gift of the ProtectorsTCoE: This is a decent support option, but it’s one of the very few Warlocks have access to. Support isn’t really your thing, so this is a bit of a stretch.
Minions of Chaos: Tasha’s Cauldron of Everything added summon spells to the Warlock spell list, so if you have access to those spells, this is obsolete.
Otherworldly Leap: You can cast fly.
Whispers of the Grave: You become a perfect homicide detective, able to speak to every corpse you come across.
Bond of the TalismanTCoE: This is a powerful teleportation option. It’s more useful out of combat, but still useful to make a quick getaway.
Lifedrinker: Pact of the Blade and Hexblades specifically must must MUST take this invocation. It’s by far the strongest and most efficient means of increasing your weapon damage.
Chains of Carceri: For such a high level invocation, there are a lot of restrictions on this. If you’re fighting the right creature types very frequently at this point, it could prove to be very useful. If not, skip it.
Master of Myriad Forms: You already have access to Mask of Many Faces and this only improves on that slightly.
Shroud of ShadowXGtE: You can basically always be invisible.
Visions of Distant Realms: You should have this active at all times if you can help it. You will hardly ever be ambushed by magic or anyone carrying a magic item.
Witch Sight: Arcane sight is better than see invisibility, since theoretically you’d see the aura from an invisible creature and everything else magical as well.