Hi and welcome!
If you want to get better at the game, there are some tips here
. I think there are some older threads, too. If someone always kills you, spectate him and try to see what he is doing, and what he is not doing. What you won't see are the most important things, like knowing the map, how other players are likely to move around it, which sounds or lack of sounds that he uses to understand where other players probably are, etc.