Be aware of the placement of your pieces
In my last game, i probably made only one big mistake which was not so easy to make out as one for me for a long time. I was really wondering, where i misplayed, where i left my winning chances, but in retrospect i finally found my mistake way back in the opening as early as move 6. I misplaced my queen there and boy did this one queen move disturb my coordination later. I could have played the game without this move as it was neither forced nor certainly threatening, i just misevaluated the positions my pieces would like to be in.
So the lesson for today: Mind your piece placement, don't put them on fancy squares just for the sake of it. And it doesn't hurt to remember the basics like "minors before majors". Would definitely have helped me in this game.
Have a nice day,