Good answer from BrokenPen. A lot depends on how high the blood pressure is.
It is always good to live healthy and maintain an appropriate weight, even you still need anthypertensive medication. You might require less medication, if you do the things that BrokenPen mentions. You also might live longer and have better quality of life by doing these things, regardless of whether or not you still need to take antihypertensive medication. Or you might need medication now, but maybe you can reduce or drop it later on, if you take good care of yourself in other ways.
So it's not a question of either/or (lifestyle or medication), it's a matter of living well regardless and taking medication if you have to.
First of all, you need to know if your blood pressure can only be controlled by changing your lifestyle or is it very high and needs medical treatment. Very high readings of blood pressure can be very hazardous if not medically, since diet control will minimally lower it.
If your readings are not very high, you can start by avoiding:
1- saturated fat.
2- Red meat.
3- Fast food.
4- Fried food.
5- Smoking.
6- Stress.
You can start to minimize the amount of salt you use in your meals, but don’t stop it. Your body needs the essential elements found in the sea salt.
You can eat as much as you want of fruits, vegetables, fish and poultry.
One last thing is exercising. Walking has been proved to control the level of cholesterol, blood pressure, blood sugar and even improve asthma. A 30 minutes walk daily should keep you healthy and highly spirited.