All great advice here and agree with it all.
Here are a several pieces of advice I was given as a BR1...
Never, ever, ever, go in first... Let someone be the bullet shield and follow them in.
Never stand in front of a Max, they will fire at some stage.
Always hit Q to spot enemies.
Have a play with all the classes, see what appeals to you and your play style
Dont worry about your K/D. Chasing a high K/D will force you to play conservatively and hinder your potiential.
But most of all... have fun
The kills will come once you are comfortable with your character and your weapon/s.