In general, the best things to do to lower blood pressure are:
1) If overweight, weight loss can significantly lower BP.
2) Reduce daily sodium intake to less than 2400 mg (that's 1 teasoon!) and includes not just throwing away the salt shaker but reading all labels. There's an enormous amount of hidden sodium in ready-made baked and processed/packaged foods. Salt is a tough habit to break but it's worth it, particularly if your wife is what they call a "salt-sensitive" hypertensive.
3) As cflas said, exercise is a winner. Daily aerobic exercise (even simple walking) 30 mins a day on most days of the week does wonders for blood pressure (and cholesterol).
4) Eat less red meat and more chicken and fish. Lots of fresh vegetables, lots of fruit. Bake or broil..don't fry.
5) If a smoker, as difficult as it is, absolutely try to quit.
6) Alcohol in moderation
7) Avoid over-the-counter medications that contain decongestants, which tend to elevate BP.
8) Stay away from licorice (believe it or not). It raises BP!
One more thing about diet.... the DASH Diet (Dietary Approaches to Stop Hypertension) has been very successful and clinically proven to lower many people's blood pressure so significantly that they no longer NEED medication. You guys could check it out on the Web.
Zuzu posted an excellent list. I can make only one other suggestion. Check her current medications, as some of them might increase blood pressure. Some over the counter or prescription pain meds can increase blood pressure, as can the birth control pill with estrogen, and HRT which is estrogen replacement.
Actually one more suggestion. If she snores or has sleep apnea, that can also raise blood pressure.