At the store you’ll often find handy signs hung above the potato bins, including how-to-cook information that’s based on the type of potato. Potatoes are placed in one of these three categories.
•Starchy (or floury) have low moisture and high starch content and include potatoes such as russets or Idaho potatoes. Bake, fry, or roast these.
•All-purpose are balanced between moisture and starch. Yukon golds, fingerlings, and purple and blue potatoes are in this grouping. Sure you can bake, roast, or fry these potatoes, just expect a creamier, moister, chewier texture (when fried) than starchy potatoes.
•Waxy have high moisture and low starch content. They keep their shape when cooked in water making them a top choice for potato salad, parsleyed buttered potatoes, chunky smashed potatoes, or thick and rich mashed potatoes. Excellent for roasting—just be sure to spread them out on the pan. If potato pieces are too close together they’ll steam.

In the Bag
A good rule of thumb is to buy a 3, 5, or 10 lb. prepackaged bag of potatoes only when you can use them within a week or if you have a cool (50°) and dark area for storage. You will get a price break over hand-selecting individual potatoes. Here’s the challenge: determining through the bag the quality of each spud. A plain plastic bag with no airflow allows moisture to build and may cause rot. Look for perforated bags, mesh plastic bags, or, even better, a paper bag with a string-like mesh area.