don't discount potatoes... sweet potatoes are better and lower on the GI scale, but regular white potatoes are not a bad choice, just make sure you eat the correct portion (ie: don't go hog wild and eat too much) and don't load it with butter and sour cream

regular white potatoes have a lot of good vitamins, especially in the skin
the items you should stay away from in terms of carbs are anything that is over processes, like most store bought breads, cereals, breakfast bars, etc... if it has added sugars, processed flours, etc., then try to stay away from it... potatoes are all natural so are okay, just make sure to watch your portions and you'll be fine
a good rule of thumb that will help to clean up your diet is to think about eating 'close to the ground' which just means, as natural as possible... if it's been packaged for your convenience in nice little ready to eat packages... it's probably not very good for ya