A lot of it is just not knowing a lot about the game in general. You don't know what type of playstyle will suit you best until you have logged in a decent amount of time.
And then there are dumb mistakes - I never noticed I had a limited amount of blocks until there were only like 4 left.
I put skill into certain things that I find myself never using and would like to put it into other stuff I use more often, but I didn't realize that when I was making my MyPlayer