A lot of good advice here. I'll just add that I think it is important to be self aware. In fact, I think it's really important.
Day trading involves quick decisions. I was just reading another thread that talked about over trading and other things. If a day trader loses his/her 'cool', if often leads to bad trades. So it's important to be aware of your mood etc. This is much more difficult to control than it sounds. Taking a loss is not easy, and then not letting it get to your head is even harder.
That's losing their self-control and lead to emotional trading which will directly lead to a lot of losses. First thing first is to set your mind when trading, do not feel any emotion connected when the market is not on your side. Day trading is a bit hard if you are just doing the basics, practice trading more often but handle the risk safely.