1.As a beginner Play open games and then go further with moves like c5 etc..
2.It is better to put your knights out before your bishops..
3.Don't pin your opponent's Knight before he castle especially you castled.
4.Make your sacrifices worth as much as possible.
5.Don't try to win your opponent in 4 to 5 moves using #scholar mate.
6.Don't bring out your queen early into the game..because it may be captured by traps.
7.Don't move your minor pieces over and over at the openning of the game unless you don't have to move.
8.Don't lose your tempo(time) by useless pawn moves.
9.whenever you are accpeting the Gambit and you are up in material say 1 pawn majority..thats completely okay but you need not to hold on to that extra pawn. Because you may lose your tempo or you may behind in developement or you may even caught in a trap or may be deflected..etc
10. Don't lose your bishops early onto the game.Once the game opens sooner or later Bishops will be powerful.
11.Try to have a Knight over a bad bishop in the end Games.
12.Try to castle your King and get him to safety asap.
13.when you are down in material with 3 points...you need not to resign quickly ....you may resing if your position is hopeless,especially when you are playing against strong player than you.
14.Don't waste time..give up soon in lost position.