How to change yourself.. ?

I am 30 years old, and am sigle, am sure that there is something wrong with the way am thinking and decisions i made in life... but just don't know how to figure it out.. I may repeate the same wrong actions and take the same paths in life.. how to know that am right or wrong in life and how to change the way of thinking so not to make the same mistakes again... How to change yourself.. ?
The thing about life is that you can never know what you're doing is right or wrong. There is no inherent value of right or wrong in any decision, just the value you appropriate to it. Some things are up to us, and some things are not up to us. Progress is made by a single day and a single action. Don't neglect yourself.How to change yourself.. ?
whether single or married everyone has his own personality,be sure about onething ,NEVER REGRET,it only brings frustrations just make a list of do';%26amp;dont';s for yourself ,thus every time a new thought erupts pen it down %26amp;think about its outcome never about what happened last time,always trust your conscience if it allows follow the route else forget the path
Unfortunately it is very difficult for people to change once they are in their thirties. But luckily for you, you may still be able to change since you're not yet the at the emotional level of a thirty year old. Look to the relationships that you currently have with people and ask yourself if you are satisfied or dissatisfied. If dissatisfied end the relationship. Meeting new people will make this much easier.