There must be a foolproof way to change myself
 

I need to be more positive and proactive.

I just slip into negative behavior.

What to do once and for all?
I want to live a great life.
I want to be great.

Nothing is foolproof but if you want to increase your chances, you would have to start hanging around with people that you want to be like. Getting with like minded groups is pretty well the best way to adopt changes that you want to make in your life. Also important to stay away from those you don't want to be like.

^agreed

also Its important to appreciate the process

What if they don't want to hang out with you?
I may want to hang around with that cute blonde in the office, but what if she doesn't give me the time of day?

Your efforts to change are your greatest negative behaviors. Number one, they fail, otherwise they would have worked and you wouldn't have to ask us for this kind of help.

Number two, the actual effort to change is itself keeping you from being the person you want to be. Would the person you want to be always be trying to change himself? Of course not. He would be the person he wanted to be. The greatest indicator of a person who isn't who they want to be is that they try to fix themselves. If you want to be like the person you want to be, then stop trying to fix yourself, and that's who you'll become. By definition, a person who does not need to change himself is the person he wants to be.

The best way is to practice getting into a certain mindset or perspective. The more you begin to see everything a certain way, the more you change.

So if you are negative, try to think positive every now and then. Meditate on some positive ideas and try your best to see the positive side of things. If you do that long enough, you will be training your mind to be more positive.

That a completely different subject.
If you want to hang out with a cute woman because you are interested in her you get resistence.
Both in yourself and in herself.

If you go to a group that about some personal development topic and say: "I'm here to change", they usually welcome you with open arms.
Especially if you follow their guidance. Don't argue their suggestions but follow them and they will mend you into a different person.

Taking NLP seminars and joining NLP practice groups would be one way.