If your roasted potatoes don't turn out browned and crispy, my first guess would be that it has to do with the temperature of your oven. I suggest roasting potatoes and veggies at no less than 400° F. It's important to preheat the oven in advance so that as soon as you place the tray of potatoes and vegetables in the oven they get right to browning properly and cooking. Add some type of fat, preferably a healthy fat such as extra virgin olive oil or grapeseed oil helps the browning and crisping process of the potatoes along. Last, make sure the potatoes don't have any excess water on them when you toss with them with the oil and put them on the baking pan.