The Witcher 3: Wild Hunt Guide to Character Progression

Introduction
Like many RPG games The Witcher 3: Wild Hunt has extensive character development and levels. Unlike many games, however, gaining levels doesn't give very many character stat benefits by itself. Witcher 3's character development is almost entirely based on an unlock-by-level system; the higher your level, the higher the level (and therefore stats) of the equipment that you can wear and the more skill slots you unlock, on top of the additional skillpoint per level. So to understand this you also need to understand the Equipment, Abilities and Mutagens that fuel it.

Equipment
Geralt 's strength growth from equipment is fairly straightforward: the higher his level the higher the level of the equipment he can wear, and higher level equipment has better statistics. There are also several different grades of equipment for each level.

Weapons
Your main tools for inflicting death on your opponents, and you'll be using them extensively. Some more advanced weapons also come with upgrade slots, allowing you to put in one of the sign Upgrade stones (explained further in the Armor section below) or one of the more powerful Runestones that can have one of a much wider variety of effects.
 * Steel Swords: Your primary weapon against non-magical enemies such as people and animals.
 * Secondary Weapons: A mixture of weapon types including axes, staves and clubs, but despite the name you can't actually dual wield one of these with your steel sword; equipping one replaces your steel sword, and they often work differently.
 * Silver Swords: Your primary weapon against magical/undead enemies. Going by the numbers these have significantly higher DPS values than equal level Steel swords, but the undead enemies they are intended for also have higher health to compensate for this so don't expect to mow through them quickly.
 * Crossbow And Bolts: You obtain your first crossbow during your hunt for the Griffin, and interestingly enough you can still fire it with no Bolts equipped; you have an unlimited number of basic Bolts available which add the lowest possible damage boost to your shots. You can craft/find/buy better Bolts and equip them for more damage to your shots but Witcher 3 does have ammo consumption for the special bolts, so once you run out you'll have to get more or rely on the basic bolts alone. This will be your primary ranged weapon, however note that in general the Crossbow even with good bolts does significantly less damage than your swords, and even several of your Signs. Note also that the Crossbow can be used while you are piloting a boat, and is in fact the only weapon or Sign that you can use while doing so.
 * Bombs: You have inventory quickslots to equip two of them. Forged through Alchemy and thrown like a grenade, there are various types of bomb that can damage or stun groups of enemies. Once created at least once you can restore your quantity of equipped Bombs through Meditation if you have alcohol in your inventory, however you can never hold large numbers of them and therefore won't use them heavily in combat, but there is one other key note on them: the Grapeshot and Samum grenades are among the only things that can destroy a Monster Nest, so make sure to have at least one of them on hand.

Armor
You have 4 armor piece slots: chest armor, pants, gloves and boots. That by itself isn't particularly important; what really matters is which of the three armor Types each piece is and how this ties into your Abilities, since there are certain ones that when fully trained give you strong bonuses per piece of a specific armor type that you are wearing. Since you don't get enough ability points throughout the game to max out every ability nor enough slots to wear all of the skills you should pick one armor type based on your intended playstyle and stick with it to make it very strong; it will literally define how you approach every fight you get into. Armor also sometimes comes with enhancement slots, allowing you to inset one of the Sign Upgrade stones that are usually dedicated to improving a single sign intensity. Be sure of when you want to do this; removing an upgrade stone destroys either the armor or the stone at your choice.
 * Light armor gives the lowest defensive boost, but when paired with the proper abilities gives the highest general combat damage boosts by heavily improving your quick attacks and critical damage. You will need to get quite comfortable with the dodge and roll moves to make up for the lack of raw protection, which makes this build and corresponding fast-attack-and-dodge fighting style surprisingly similar to combat games like Devil May Cry.
 * Medium armor gives moderate defense and strong boosts to your Stamina regeneration and Sign intensity, making it an ideal choice for people who want a more mage-like build firing off strong Signs as often as possible.
 * Heavy armor gives the highest defense, boosts your maximum Vitality and also boosts your Strong attacks, leading to a slow-but-steady tank-like style of fighting.

Accessories/Consumables
On top of your armor and weapons you have an extensive array of supplementary equipment and items available to you, some of which actually get equipped on your horse Roach.
 * Consumables: You have 4 quickslots available to you with hotkeys set on them for quick use, and you can equip any food or potions in them. This will be your primary source of healing for a fair chunk of the game.
 * Saddle: Equipped on Roach and starting off with an initial basic one, this mainly determines the maximum Stamina Roach has when you have him go at a full gallop before he gets tired.
 * Saddlebags: Also equipped on Roach, this mainly determines the maximum weight of items you can have in your inventory. Some items like herbs and quest items are considered weightless so you can have mountains of them in your inventory, but equipment isn't so you'll want a good set of Saddlebags to prevent yourself from having to go back to a merchant to sell your loot too frequently. If you are holding more weight of inventory than your max capacity you lose the ability to run, sprint and jump while on foot; you can only move at a walk. However, you can still ride at full speed on Roach.
 * Trophy: Usually a body part of some legendary monster (eww) that also gets equipped on Roach, fully visually rendered tied onto the side of your horse in all its gory glory (ewwwww), these give a variety of permanent passive effects such as increasing your chance of beheading enemies on a hit, boosting your experience gain, etc...you get your first one after defeating the Griffin.
 * Horse Blinders: Somewhat obviously equipped on Roach, this headpiece primarily reduces how quickly your horse's Fear meter grows in combat.

Abilities And Mutagens
Abilities are a set of passive boosts that can affect every single aspect of your gameplay, and you purchase/upgrade them with Ability Points gained through gaining levels and obtained from Places of Power, and fitted into Ability Slots. You unlock a total of 12 AbilitySlots in sets of 3 throughout the game at levels 2, 3, 4, 6, 8, 10, 12, 15, 18, 22, 26 and 30. There are three main Ability Groups of Combat, Signs and Alchemy that each have five Subtypes, and a fourth smaller group of General Abilities.

Mutagens are very rare Alchemy ingredients that are so strong they can actually be worn like equipment for permanent passive boosts. You unlock up to 4 Mutagen slots, one for each Ability set of 3, at levels 3, 9, 16 and 28. The connection with Ability sets is important; each Mutagen is a specific color matching one of the Ability Types (Red for Combat, Blue for Signs, Green for Alchemy. General has a unique color that doesn't match anything), and if you equip Abilities of the matching color in the same set as the Mutagen that Mutagen's effect is boosted by 100% each. Mutagens are also key ingredients of Mutagen Decoctions, which are like Potions but with stronger and much more long-lasting effects. Some lesser magical enemies also drop lesser Mutagens that you can combine into stronger versions for a stronger effect.

The planning of your Ability build is one of the most important aspects of the game, as well as one of the trickiest. There are 70 Abilities in total; you get enough slots for 12 of them and you can't swap them in the middle of combat. You would also need several hundred Ability points to max every ability; you can only get a total of 85 throughout the entire game, and each of the three main ability Types has four Tiers that are only unlocked if you invest enough Ability Points in that group. So before you start investing points in anything, really read through the effect descriptions of every Ability (paying particular attention to the three General ones that boost depending on the armor you wear) and plan out what kind of a fighter you want to be.

SIGNS
This is already covered in The Witcher 3: Wild Hunt - Guide to Witcher Signs and will not be repeated.