Up and Down

I play a lot of games on chess.com, but it's clear that I'm not a very good chess player.  I make a lot of stupid mistakes, and I miss a lot of good moves.  My rating is slowly improving, but it sure goes through a lot of up and down along the path.  I'm often the low guy on the totem pole in any given tournament, and those 1600 level players tear a 1200 like me all to pieces.  

Probably the biggest weakness I have is simply that I have no idea of how to make a plan.  It seems my opponent always does something different than what I expect, so no plan is worth anything.  I have a really hard time looking further than one or two moves, and sometimes I can't even see THIS move, let alone the next one.  

I play a lot of Tactics Trainer, and it's very frustrating that I can't get my rating to stay over 900 no matter how hard I try.  

So, if there's anybody else out there that simply can't seem to get over a hump, believe me, I know how it feels.