1. Practice
Nobody became amazing at the game overnight - everyone started off as a noob, walking in to walls and blowing themselves up. But if you learn the maps, remember the corners where the campers always sit, experiment with the guns and accessories to find the classes that suits you, then you should hit the ground running. Putting all these tips in to practice will get you to level 50 in no time.
Do you have any helpful pointers to add? Let us know in the comments how you achieved world domination online!