I got my 255 through sheer persistence. I'm not "gud" and I doubt I ever will be. That's one of the reasons I prefer to make things in the social district. When I do go and do missions, I get stomped on, it isn't fun and I have never - NEVER - seen anyone try and offer advice to newer players on how to improve.
I'll try an analogy and hope it clarifies the frustration that I'm sure many players feel after getting stomped on by better more effective players.
If you blindfold me and send me down a corridor with a tripwire. I'll eventually learn to be careful and learn where that tripwire is.
If you keep moving said tripwire and then, say add someone with a bat to smack me in the face at random down that corridor while I'm blindfolded, it's really not going to be easy to learn to avoid that without someone telling me what's coming.
I'll really never do well until I can either remove the blindfold, or be given a stick to find the tripwire or the person with the bat.