what am I doing wrong

I have had numerous games in the past couple days and every game seems to be going south i am getting beat! I cant say that I find this surprising because of my recent concentration level but I seem to be doing a move that is devastating that all partially seasoned chess players seem to jump on. I am not sure whether it is a lot of blunders that are collective that cost me. What ever it is i would like some feedback and i appreciate all constructive criticism