No matter how I try, I still drop pieces in most idiotic ways. It's not the complex combinations that kill my games, but the braindead one-move blunders. Like a couple of days ago, I was two minor pieces up, when I dropped my queen. I was not even moving fast, I really had thought about the position for some time. I also saw the check coming, figured out variations it brought, and then just landed my queen right into one-move knight-fork with the king. And as usual, about 2 seconds after moving I realised what I'd done. And I do similar blunders a lot, almost all of my losses happen because of such simple errors. It doesn't matter if my opponent is 1300 or 1700, I rarely get outplayed positionally, instead I drop a piece and that's that.
So, today I finally decided to start routinely doing a blunder check before I make the move. It's surprisingly hard to remember, but I try to do it on every single move. Hopefully it'll grow on me. I already caught one possible knight fork, so it's starting to pay off immediately.