0Moving the same Piece more than Once in the Opening:-
Moving with the same piece more than ONE time in the opening of the game loses development time and may lead to an inferior position right from the start.
Just thinking about your own Moves:-
Just thinking about himself without considering the chances of the opponent is a vital mistake. This leads to falling into traps of all kinds, like forks, double attacks, checkmates etc.
Neglecting Development of Pieces:-
No development of pieces is a fatal mistake in chess. (pieces are bishops, knights, rooks and queen, NOT pawns) Don't keep pushing pawns, but get your pieces out fast and castle early.
No Center Play:-
Many players put their pieces on bad squares where they don't control important center squares, diagonals, or files. Some players put the knight on the edge of the board. If you do this your opponent will get a lot of power in the center and runs you over.
Pushing too many Pawns in the Opening:-
This weakens important squares and diagonals and the opponent can penetrate with his pieces which leads to loss of material and the game. Fact is, that every pawn push weakens squares. It is a matter of evaluation which pawns should be pushed and ask yourself if the weaknesses created are less important than the advantages you will get. Everything is relative in chess. When you push a pawn in the opening you could have developed a piece instead which is far more powerful than "developing a pawn". Simple logic.
You should push just one or two pawns in the beginning of the game to get your bishop out and to be able to castle. Bishops can't jump over pawns, so you must push a pawn to get a bishop out. That's all!
