This one, I warn you in advance, is going to require more lead time unless you want to go and stock up on vegetables today just for stock. Better: starting today keep a gallon ziplock in the freezer with the trimmings from veggies you prep for other things--onion ends, bell pepper caps, celery ends, brussels sprouts stem ends, etc. just about all of it. When the bag is full, it's time to make stock. Put all of that stuff, a chopped carrot and an onion plus a couple of teaspoons of salt, some pepper, any fresh herbs you like into a large pot with 6-8 quarts of water. Bring it to a boil, then reduce heat and simmer until it has cooked down to half or so. You'll wind up with 3-4 quarts of stock for other things. Let it cool and freeze it in quart size ziplocks or containers.
Easier still. Make one of those chickens under a brick and save the carcass, or save all the bones from any full-size chicken meal using bone-in chicken. Break the larger bones so the marrow will also flavor the stock. Add salt, pepper, herbs you like (esp fresh ones), boil in 6-8 quarts of water, reduce and simmer until it's cooked down to half the volume. Store as above.
This one I like to make on the spot for paella with whole fish and/or head-on shrimp in their shells. Put the fish head(s) and shrimp heads into a gallon or so of water with the shrimp shells, some liquid smoke, salt, pepper, etc., boil, reduce and simmer. This is the best stuff to use in making paella. Speaking of which, I'm working on a paella recipe, coming soon...