I was good in crysis 1 mp but now I think my avg kills/deaths ratio is like 4/15.

At the same time while it being very frustrating, it`s starting to have funny elements cause I can`t help myself laughing out loud when I just keep ketting killed all time long and when I shoot somebody in the back he turns around and shoots me with 1-2 shots. =D

So hilarious tell me what am I doing wrong most likely.

Try to adapt. In the beggining i had the same ratio. Now i play 20/4 - 20/6 but global ratio is only 1.84.

Yeah but it`s just funny. As if other players were more powerful than me. Especially in situations where I clearly get the first shots, aim at head etc, yet they just turn and smash me. I know I just need to improve but also all these posts about players cheating make me paranoid.

When you're starting off you will be at a disadvantage. You're using the early guns with little useful attachments, you're using the early suit modules at level one and it seems the way the suit works has changed since the Nanosuit 1.x in Crysis so there's a bit of a learning curve.

But don't get discouraged, just get whatever kills you can and you'll slowly unlock everything you need to get good combinations for taking on the competition. Always save a weapon/attachment/module token until you absolutely need it, since when an equipment piece finally gets unlocked from getting a rank you won't be stuck having to wait til the next rank or two to get a token for it.

When levelling modules for the first time, keep up a certain level of perkitude by keeping a level three module equipped while levelling the other two. Levelling modules three at a time will leave you at a disadvantage. Extended Mags for weapons is generally an all-around good choice for many weapons. Ammunition attachments like the light-shotgun and grenade launcher can be good for getting extra experience when you kill with them to climb the ranks.

Silencer is also a useful attachment for staying off the radar when you fire shots, and in the case of the DSG-1 sniper rifle, has no damage reduction at distance! (Silencers reduce the minimum damage at distance, but not the maximum damage at close range!)

Try checking out the available skill assessments and try to achieve the non-obvious ones like Sprinting and jumping (falling). Also when your options start opening up, try equipping modules that patch up the weaknesses in some weapons.
Like Marshall + [Rapid Fire] or
K-Volt + [Point Fire Enhance] or even
Mod 0 Heavy Machinegun + [Weapon Pro]