Salt, exercise, genes. Part of blood pressure regulation is genetics. If you have a genetic predisposition to get high blood pressure then you may have to deal with that issue. After that, getting regular exercise and cutting down on salt can help. In addition, maintaining a normal body weight and avoiding caffeine and alcohol can also help maintain a normal blood pressure.
Regulation of BP. Your question is too broad to answer here. Be specific and focused. Regulatory mechanisms are too broad to describe here. We can control high blood pressure with diet, exercise and medications.