1) Limit processed carbohydrates - bread, pasta, rice. To zero. Use higher fiber alternatives - whole wheat/grain bread and pasta, brown rice, higher fiber alternatives like barley.
2) Protein is great - just limit the fat. I don't worry about white or dark meat - it just has to have no skin and as much apparent fat trimmed as possible. Eggs are great, Beans are awesome. Tofu is ok, but hard to cook and really not that low in fat. Cheese - well, really hard to trim fat from cheese - plus most low/no fat cheese really tastes terrible and doesn't melt.
3) Fresh vegies and fruit are your friends - no limits. This includes potatoes. However, juice is terrible for you - it is not the same as fresh fruit/vegies. Basically it's sugar water.
I try to construct meals with this formula - 1- 2 - 3. For every one processed carb serving, the meal should have two proteins and four vegies/fruit. Ok, so that is really more like 1 - 2 - 4. And no meal should have more than 2 oz of processed carbs.
The final key item with this is sauces - it really does you no good if you eat a lot of vegetables but then serve it in a sauce that is high in fat or in sugar - or both! But that is for another post....