You can start with 2.5 mg at bed time initially (Max effect of the drug should be present in Early morning hours) and check your Blood pressure at several times .If it reaches 130/80 you can continue that. Otherwise You have to take 5.0 mg at Bed time and Check your BP. You have not mentioned your Age. If you are a person with lot of psychological tension Your BP will Vary depending on Your Tension. So You have to control your Tension by Meditation/Physical exercise. If you tension does not subside with Your effort You will have to take drugs to reduce your Tension Otherwise BP will not be Controlled. You have to reduce salt in your diet
. You have to reduce your weight if you are overweight. Control Diabetes
. Should avoid Hypoglycaemia.