If you neglect to buy any other spices of this kind, you should at least buy this one. Fresh garlic, actually a member of the lily family, is preferred to its processed counterparts. Garlic is an integral flavor addition to a variety of dishes. You should always have a couple of onions on hand. The four main varieties of onions are red, yellow, white, and green.
Red onions are usually milder in flavor, and better for eating raw, as in salads.
Yellow onions are the least expensive, and, I feel, work best for most cooking purposes. As for large white onions, no one really seems to know what they work best for, but they are the most aesthetically pleasing to to use as kitchen decor. From fried potatoes to Bloody Marys, Tabasco sauce is your friend. It is hot and vinegary, adding piquancy and flavor to a variety of dishes. Accept no substitutes.