Just like boxing, basketball, baseball any other sport there are fundamentals we should follow. As you get better and better you'll learn how to manipulate and leverage these fundamentals!

First off, if there is one rule you should follow above all else it is this.

                         "What is my opponent's plan?"

Start every move with why is my opponent playing this. Whether your opponent is making a good move or a bad move try to understand what that move does, then you can go ahead with your plan(this same principle can be applied to life).

Opening Principles
1.Attack/take control of the center
2.Develop your pieces 
3.Castle early 

4.Attack your opponent's king

Rules you shouldn't break
1.Don't bring the queen out early
2.Don't move the same piece twice until all your pieces are developed

Attacking Principles
1.Bring more pieces into the attack(generally at least 3)
2.Don't go for cheap tactics if it makes your position worse.
3.Use your pawns to open up your opponents king
4.Don't be afraid to sacrifice material to open up your opponent's king. 

Thought Process
1.What was my opponent's move
2.What is his plan?

3.What is my plan?

4.How will my opponent stop my plan?

5.Is my move safe?