Each time you blunder a piece, go back, and ask yourself what you were thinking about, besides piece safety. You were probably looking for some subtle strategy, or some dazzling combination. Whatever it was, you need to learn to put that stuff on the back burner. Not blundering pieces should be your first priority! Everything else should come second. That will win you more games than anything else in the world.
The way you explained it is my way of believing that it is good to be patient and disciplined in your thought process when it comes to moving your pieces to the best squares that effectively help in carrying out a certain strategy or plan of attack. Especially, if you happen to play a lot of different players for the first time. I definitely will remember your advice about not blundering being the first priority.
Thanks, varelse.
To everybody who advised me: The advice is working right away. Here is proof:
By following your advice, from looking for what my opponent will do and to prevent him/her from doing that, to sitting on my hands, I think that this is immediate proof that I have been given sound advice that will improve my game. With that, I say thank you, and maybe I will eventually be good enough to be able to play against you guys thanks to you and others like you who help players for the good of it.