How can I become better?

Good question! Many of us are asking that same thing.  I'm starting to get better. I usually get 1-2 kills. But one 'reply' you got was akin to what I'm seeing as I'm getting better.

Don't rush into something, especially after you died and respawn, take time as you can. Yet, there are other moments you have to be aggressive by moving slowly with your gun sites up ready to fire. Many times I can't see them in time to get my gun up before they kill me...not fun.  I liked what that same reply said, learn a play style that works for you and if you can, stick with groups of people.  I found being medic and engineering support with a group can be kind of exciting!

There are players here that are so fast, so good, they run and fire hip, they know the maps and every hiding and cranny to fire at you, they use gadgets like grenades effectively too, and teams that keep winning run around killing in groups of 4 to 5 -- I've noticed.

After respawn I'm going to try to get with a group of 2 at least and try to work together and certainly remember they might be in a 'nook and cranny' on the floor with gun aiming just waiting for me to poke my head up!

It's fun and many times aggravating. At times it's a #$#@@ game, but, enough excitement in it, and a 'real' factor, and enough success if you learn from the constant dying that you can find out what works better?

You will most likely die a lot though every time you play but less when correctly with working with teams.