Cooking for one or two seems daunting at first, I know I was intimidated, but I soon realized that it's mostly a matter of math and a little more planning than cooking for four or more.
First, many packaged quantities are made for larger recipes than a single person wants to prepare for themselves, even with leftovers. I like peas, but I don't want to open a can of peas, using just half a can and having to refrigerate the rest until I decide to use them again. Who knows when that would be? And I may not want them stored in the open can. That could mean a host of storage containers with food of unknown age scattered throughout the refrigerator, or freezer. I now buy a bag of "frozen peas" and pour out the amount I want, then returning the balance to the freezer. The same goes for hamburger patties. Frozen and only remove one or two at a time.
If I want a meatloaf I only buy 1 lb. of beef and 1 lb. of pork. I don't buy the 2-2-1/4 tray or 5 lb. roll. I only buy for that meal. If you don't see a smaller package in the meat case, talk to your butcher and have them grind you the small amount you want. Many times, it's better than what's in the case already!
For many recipes, cutting the listed quantities in half is acceptable and will get you the desired dish. Just realize that common sense may have you adjust (by experience) some ingredients, particularly liquids. Not always, but sometimes.
I often use a crock pot - a 2 quart crock pot (1/2 normal crock pot volume). That way, I'm not able to make more of a soup, stew or chili than I can deal within a short amount of time. Instead of buying a package of carrots, I buy two or three individual carrots. Instead of buying a bag of regular potatoes, I buy a small bag of fingerling potatoes, or even one baking potato. It's strange, but when I shop I often buy LESS than I think I need. And more than not, it's just the correct amount.
Expect to throw out food (or feed the dog well) if you don't shop carefully. I will sometimes get a craving for a bologna sandwich. Buying a package of bologna and making a couple of sandwiches from it satisfy that craving, but then I will often ignore that bologna for a long time after that and it goes bad before I use the rest of it. That goes for any refrigerated food, so when you shop, be certain that whatever and however much you buy is going to be an amount that you'll likely finish before it goes bad... or be willing to suffer the financial loss later.
There's more than this to consider, but it should get you started... with confidence.
"Food is our common ground, a universal experience." - James Beard