Stay away from processed foods to keep your sodium in check. Also make sure to compare the labels of reduced fat foods. I started noticing that the difference in calories was minor but the difference in sodium can be alot. Low Fat cheese is a good example. I have no problem keeping my fat in check so I quite buying the low fat versions in many cases.
Not all people wtih High Blood Pressure have sodium induced HBP. But if you fall into that category, the recommend limiting to 1500mg which must be really tough to stick to.
Also keep your table salt to a bare minimum. A 1/4 teaspoon has 581mg or 1/4 of your daily total.