Hit Dice: d10 is pretty standard for martial classes. Some of your abilities rely on you sacrificing your own hit points, so having a lot of them is crucial.
Weapon Proficiencies: Martial weapon proficiency gives you a great selection.
Armor Proficiencies: Light and Medium armor proficiency means you have to choose between a Dexterity/stealth build as an archer, or a melee-medium armor build.
Tool Proficiencies: Having proficiency with a rare tool set like Alchemists’ Tools means you can craft interesting things like Alchemist’ Fire and other tinctures that most classes do not have access to.
Saving Throws: Dexterity is the most common save, and given your propensity to Archery, you’ll be particularly good at evading traps and spells. Intelligence saves are less common.
Hunter’s Bane: You are really, really good at tracking fey, fiends, and undead. In a campaign full of these types of creatures, you’re going to go from prey to predator very quickly.
Blood Maledict: Your Blood Curses are magic-that-isn’t-magic. You have access to a few at first level, and get more as your progress. The option to enhance them is similar to a Sorcerer’s Sorcery Points, but it’s your life, not a secondary pool of resources.
Fighting Style: You have a bunch of weapon-centric options to choose from here. The Dexterity Build wants you to take one of the first two to maximize your damage.
Archery: Accuracy is important. You can’t damage an enemy if you can’t tag them.
Dueling: Keeping one hand free allows you to hol a shield, or use other trinkets.
Great Weapon Fighting: Yes, Geralt uses two Longswords. No, you shouldn’t do that. Removing Strength from the character-building equation gives you more focus on what really matters.
Two-Weapon Fighting: To get the most attacks overall, and make best use of your Crimson Rites, choose this one.
Crimson Rite: The bonus elemental damage from this ability makes it worthwhile to dip into this class from any martial class, and getting larger hemocraft die make it worthwhile to stay. Sacrificing a single die of hit points to deal that die of damage many times over the course of a day make it very worthwhile.
Primal Rites: These are some of the more commonly resisted damage types, but it’s magic damage on top of your normal weapon damage so it’s good.
Rite of Flame: Fire is the most commonly resisted damage type in the game, especially among fiends.
Rite of the Frozen: Cold is another commonly resisted type, especially among fiends, but less so than fire.
Rite of the Storm: Few creatures among fiends, fey, and undead resist lightning, and few creatures outside those types either.
Esoteric Rites: At 14th level you can get some less-commonly resisted damage types.
Rite of the Dead: Necrotic is a rare damage type, but it is resisted by evil things, which you are likely to be hunting.
Rite of the Oracle: Not many creatures resist psychic damage, but a lot of undead are immune to it.
Rite of the Roar: There are very few creatures that resist sonic damage. This is the best option available.
Extra Attack: More attacks mean more bonus damage from your Rites.
Brand of Castigation: Being able to mark and track a creature once per short rest is convenient, but not terribly powerful. The bonus damage is rather nice when combined with your Rites.
Grim Psychometry: A meta-ability that allows your DM to reveal some plot and advance the story.
Dark Augmentation: This is a very useful ability. Provided you’ve got a decent Intelligence, your physical saves get a huge boost. From here on out, you should prioritize maximizing your Intelligence whenever possible.
Brand of Tethering: This is great for fighting fiends and some fey.
Hardened Soul: You don’t want to get suckered into a “role played myself to death” situation, so resisting fear and charm effects puts you squarely in charge of your character’s decisions.
Sanguine Mastery: You’re going to roll multiple Hemocraft dice each battle, so rerolling them maximizes your damage output, and minimizes the hit point commitment to your magic.