I had to lose weight to lower mine, but even now at a healthy weight, this is what helps me keep it within acceptable ranges:
1) Invested in some $$$$$ spices from Penzeys. This helped me cut down on the salt I was using when cooking.
2) I eliminated deli meat, canned soup, non-fresh bread, and frozen meals from my diet. We (DH and I) use frozen or fresh veggies instead of canned. We buy low-sodium beans b/c I'm too lazy to soak them overnight and rinse them well before cooking with them. I still eat pasta and canned pasta sauce (I recommend Classico). I really need to cut back on the dairy, though.
3) Agree 100 percent with the hydration. It helps me.
4) Exercise has helped me so much. Do you lift weights/go to Body Pump? I really believe that doing this 2-3x/week, in addition to cardio, has helped my body get stronger and process nutrients more efficiently.
5) Monitoring at home. I fluctuate from (roughly) 110/80 to 125/85, which is considered acceptable by my doctor. It was helpful to show several months' worth of data at my last physical, especially since I get nervous during checkups and my BP spikes correspondingly!
I started this whole process with an average BP of 170/98, so I'm pretty proud of having controlled it. This isn't going to work forever for me (genetics will kick in), but for now, it's good.