We used our old carrot tops, onion peels, and whatever organic leftovers we have from the week and add it to a stock pot with a little water and spoices. We save meat bones or leftovers form the week. WE save it in a fridge for a day or so until something accumulates. Not more than 4 days.
We then boil everything for down for an hour or more. We then strain it with a good strainer or soon out impurities. This way we are using what we have. We just keep a bowl in the fridge and make stock one a week. Sometimes we add other stocks, bullion flavorings to our stock to prepare to make a meal with it. It keeps in your fridge for few days. It freezes well.