One of the most important facets you must know about is position, If you divide a nine seat table into three, you have early positions, middle positions and late positions.
Your opening bet totally depends upon which of the three positions you find yourself. Don't worry, because the deal rotates, so do the positions.
In the early positions you do not have a clue how your opponents will bet. A good rule of thumbs is, if you do open, be willing to bet any following raise from the others. If you can't do this then don't open
In late position you know how the others have done, you have more information to base whether or not to play