I self monitor from time to time, when I am due for a meds review.
I measure in the morning (mid morning) and take three readings with a few minutes between them, during which I relax and breathe slowly and deeply and focus on my blood vessels melting and relaxing and disappearing. The third reading is always the lowest,and I record the two lower readings (on a spreadsheet). I repeat in the evening (after a wine-washed-down evening meal which always reduces BP for me).
I do this for a week, and my spreadsheet then analyses the numbers and shows the average BP.
I don't know if I can upload a spreadsheet here. If it can be done, then I'll do it if anyone is interested. It doesn't reduce blood pressure, but it does let you know what is the average over a week.