Young Lara Croft's second adventure will see you, as the players, trying and finding new ways to improve her skills throughout the entire game. In order to do that you will need a lot of XP points which, just like in an ordinary RPG, you can gather by completing several little tasks while playing. In case you'd want to fasten that process, here's a quick tip for you to maximize your experience points in the early stages of the game. Reach the Soviet Base, the hub where the game really opens up for the first time (it's after Mountain Peak, The Prophet's Tomb, The Siberian Wilderness and The Glacial Cavern), and do what follows.
At the first base camp you'll meet, Installation Vista, head down the zipline and follow the path ahead. Stealth kill the enemy in front of the bushes, then take out the two enemies together following the tutorial's suggestions and distracting one of them. Head over the wall so you can reach a small open area with a statue and a lot of chest high walls: take out the enemies there and follow the map marker.
In the end of this section you will find a long zipline: use it and you will be awarded 75 XP for entering the building with stealth. Kill the enemies in the interrogation room and head through the air vent so you can enter another combat room. Climb through the gap in the top right corner once you have cleared the area.
A new base camp will be available at that specific point. Fast travel back to the Installation Vista base camp and get back onto the long zipline: this will award you another 75 XP. Repeat the process as many times you like to obtain a lot of experience points before you proceed through the story mode.