Homemade stock is almost always better than store-bought stock. And making your own stock doesn't need to be difficult or time consuming. With the help of a few general principles, you'll be able to make everything from chicken stock to fish stock without ever having to look at a recipe.
1. A general rule of thumb that applies to every type of stock is to start with cold water. (If you don't start with cold water, you will almost certainly end up with a cloudy stock full of impurities.)
2. Never bring a stock to a boil. This is for the very same reason as #1.
3. Perhaps most important, never add salt to a stock. When you're making stock, you're concentrating all the flavors. Salt shouldn't be one of them. Chances are, you'll be concentrating your stock further when you make a sauce or a soup. You'll want to be able to control the salt level later on.
Everything Else You Need to Know
Every meat-based stock has three components: animal bone, aromatics, and water.
The animal bones should be trimmed of as much fat and skin as possible. If you leave too much fat on, this will make for a greasy stock. Also, chop the larger pieces up — this way you'll expose a greater surface area to cooking and extract more flavor from your bones. A special rule applies when making fish stock: Always use the bones of a lean, white fish, or you'll end up with an overly fishy stock. For example, avoid using fish like salmon. Some good examples of fish to use include branzino, halibut, tilapia, and fluke.
Aromatics consist of a mirepoix, a 2:1:1 ratio of onion, carrot, and celery, and also a bouquet garni, a handful of thyme, a couple of bay leaves, and about a tablespoon of whole black peppercorns. How much do you need? Aromatics should typically weigh about twenty percent of the weight of the bones. If desired, you can add leeks, garlic, tomato paste, or a couple of cloves (cloves are very strong and a little goes a long way).
Feel free to experiment. For example, a rule of thumb I use when making chicken stock is about a handful of chopped onions, a couple carrots and a couple stalks of celery to one chicken body (which weighs about 1.5 pounds).
The rest is easy.