Tips and Tricks
Customize your HUD early on, because that can have a significant impact on your experience.
You can use an option to enable auto-shoot, which fires rounds at your enemies once you line up your shots.
Keep in mind you can shoot enemies through some thin walls and materials.
When possible use your scout drone to outline enemies and then aim for the head.
As in many games you can shoot barrels, gas canisters, and propane tanks to cause explosions and kill nearby enemies. You'll know if a barrel can be shot if your crosshairs turn red when aiming at it.
Try to find a good place to crouch behind, a knee-high pieces of cover in the environment so you can shoot without taking much or any damage.
This way you can check on enemies and aim at them when you want it and still have the safety you crave/hidding place.
There's also 'auto-crouch' (singleplayer only) which makes you automatically get behind cover when you approach an object.
General XP is earned by finishing missions, and completing those three star objectives.
You also get XP for every kill, with bonus points for headshots, explosive kills, multi-kills, and other efficient ways of murdering people.
Keep in mind that each weapon has its own experience meteras well wich means you'll get 10 points for each kill and earning those points unlocks new optional attachments for that weapon.
Also, getting kills with weapons in one class will unlock the next gun in that group.