You can learn a host of 67 new Skills, all of which can be unlocked by earning Skill Points from XP gains. Luckily, this provides no real feat - XP can be gathered from everything! Killing enemies, hunting animals, collecting resources and important items, will all give you XP towards unlocking the Skills you want most.
However, purchasing Skills cannot be done at any time. In order to unlock them you must first find a Base Camp to access the Skill tree (just like the previous games).
If you have played the previous two Tomb Raider games, then the Skill tree should be rather familiar to you - although this one has been given a whole new look.
As you'll notice, the Skill tree has been divided into three separate, coloured trees, all with their own specific perks that can be tailored to how you wish to play. In addition to this, they are also tied to abilities that can be used by specific plants (Perception, Endurance, and Focus).
The Seeker tree (blue) focuses on your surroundings, such as environmental awareness and gathering resources. This tree is most suitable for those who wish to craft and upgrade a lot of equipment, especially if they are already confident in their approach to combat.
If you want to best your enemies in combat, then the Warrior tree (red) is where your investment should lie. This tree focuses on enhanced survival and combat techniques, and comes in most handy if you're finding it difficult to survive enemy encounters.
The Scavenger tree (green) focuses primarily on stealth tactics. If you'd prefer not to go in guns blazing all the time, then invest your XP into this portion of the Skill tree. Unlike the previous games, Shadow of the Tomb Raider puts a particular emphasis on being stealthy, which gives Lara a huge advantage over her enemies.