I really like this mom's description of making stock. It is basically what I do.
Here are some additional notes about stock:
I have good jiggly stock in only 12-18 hours - depending on how diluted it is, whether I started with frozen bones or cooked chicken, whether it is first or second (or third?) batch... etc. I usually do try to go longer though. 24 hours is more ideal. The main thing is low low heat. A crock pot or a stock pot on top of cast iron pan will help have lower heat.
Cracking the bones helps release the marrow and minerals, any vinegar will help release minerals, and you don't need a huge amount. Just toss a little in with water and let it sit half hour or so before starting to heat. If it's already hot, and you don't have time to soak with acid, no big deal.
Once your tired of letting stock simmer, strain if desired, and drink/make soup, or save. Put in thick jars, and completely cool in fridge before freezing (if freezing) and freeze slightly tipped so you don't explode your jars. I have found that those nut jars or jars from my prepared-sauce days are thicker than mason jars, and freezing them tipped slightly makes a world of difference.
All the mushy bits and bones that completely disintegrate can be ground up (processor) as added bonus to thicken soups or use like bullion cubes. Organ meats I didn't/couldn't sneak into main course are easily hidden in this paté. You can even use it to make gravy!
Any kind of bones will work - however, certainly better raised animals will yield more nutrients and less toxins - esp. in regards to fats. Toxins are primarily stored in fat. You can bones for really cheap (or free!) if you find the right source. The best bones are the weird ones - knucke bones, heads, feets, legs, etc. Feet are especially good for gelatin.
You can get multiple batches of stock from the same set of bones, later batches will be much weaker. You will probably want to reduce the stock after making it.
Some people flavor the broth while they make it (with dried seasonings, trimmings from other veggies, onions, carrots, garlic, etc.) Salt should be added after finished simmering. I typically don't season my stock - I just season the dish I prepare with it.
And finally - stock is the best source of calcium and other minerals. Gelatin is incredibly healing, and stock is often referred to as the "elixir of life" - Whether you are just trying to be healthier or just save money - you WANT to add stock to your daily meals.
