Preparing to play chess (openings)

1. Moves
If you are going to play first move X( e.g. 1. e4), it is best to know (remember) at least one move ahead, - to know what you will respond to any of possible 20 moves (including all opponent moves that looks "foolish").
If you are playing 1. e4. It is good to know what to respond after all these moves: 1. e4 a6, 1. e4 a5, 1. e4 Na6, 1. e4 b6, 1. e4 b5, 1. e4 c6, 1. e4 c5, 1. e4 Nc6,..., 1. e4 h6, 1. e4 h5, 1. e4 Nh6.
For example if you are going to play 1.e4 to black move 1...e5, you might prepare at least one move, let's say - 2. Nf3.
2. Plans
The other side of your improved game is plan. The plan is what you are thinking by making certain moves. Moves can be "bad", but if you are thinking(or having plans), then you will achieve something. The more plans you have and the more moves satisfy them, the bigger chances that any one of your most acceptable(or realistic) plans will be successful. 3. Evaluations
The third part of the game are evaluations(or expectations, feelings etc. ).
What do you expect from what has happened? How do you feel in this position? What(and why) do you like and what you don't like in the position. Answers to these questions might help you to improve your plans and sequences of moves.
4. Experience
The more you know, the more objects you can put in your plans and the more accurate positional measures(evaluations) you can take. So you can put ending objects(to plan ending)in your calculations even in the opening.