Let's lay out the simple basics of manifesting:
1. Have something you want.
2. Consider that it is already here - don't worry about how you are going to get it, just concentrate on how it is, how it arrived.
3. Get the feelings of it and work at maintaining this constant attitude.
4. Surround yourself with things and activities which make you feel good. Do those things which bring you peace.
5. Be grateful for all that you already have, as well as those things coming to you.
6. Treat yourself as you would like others to treat you. Be supportive. Be kind, cheerful, positive and acknowledge all that you really appreciate about yourself. Treat others around you in that fashion in order to back up those feelings in your environment.
While you are free to think however you want, by its very nature the positive thought is far more powerful than anything else - providing you include the high-volume positive feeling that goes with it.