What is the best way to treat or lessen high blood pressure naturally im just 26 years old female not obese, does not smoke, does not drink alcohol, but with a history of preeclampsia?

Reducing stress levels, if possible, increasing or starting physical exercise, low salt diet and improving sleep quality are generally lifestyle changes that result in normalizing blood pressure. Sometimes hypertension is due to medical causes and work up might be needed in order to address properly the its cause.

Taking medication to address high blood pressure is natural. Some people have the notion that "natural" things are better. Please remember that cobras are natural too.