Decision making is affected by a wide variety of factors. Every person or group as a whole has different characteristics that dictate how one makes their decisions. Consider the following ideas.
How one's parents makes decisions
Oftentimes people learn how to make decisions from their parents just like they learn so many other lessons. They may watch their parents mull over different choices. They may make a lot of the same choices or at least use similar strategies for selecting which choice to make.
The way the society makes decisions
Different cultures actually consider decisions in different ways. Some have a longer thought-out process whereas others are known more for on the spur decision making. One might follow along with the way their society does it. Also, they may be influenced by other people in their lives such as their friends. Once you are married and you are with a spouse for so much time, you also might start to reflect his or her behavior.
Past decisions and their consequences
Many people learn from their past actions. If you made decisions in the past that turned out to be wrong and you paid for it, then you might make different decisions in the future. If your decisions have served you well, then you may continue along in the same strain in the future.
It does not have to be your own decision that lets you learn from it. For instance, if you watched your friend make very bad decisions on drugs or alcohol and watched what his actions wrought, then you might be more likely to make your decisions differently in the future.
This might actually play the most important part in decision making. Your personality is going to shape the choices you make and the process by which you make them. Some people are very impulsive decision makers. They may decide what they want right away and go for it. Others take their time and weigh every possible pro and con in order to ascertain the very best decision for them. There is no one right or wrong way because some people make the best decisions for themselves with their own method.
If you are not happy with your decision making, then you can take steps to change the way in which you make your choices. The above factors are some that may play a part in the way you do this.