During my many years of cooking, I've always used store-bought broth. But recently, I've learned that I can make one myself with all my kitchen scraps. This broth is so much better because I know exactly what I put in it. It takes some time but it is worth it. Give it a try, you won't be disappointed!
Of course, you can make your own version by adding herbs, spices, meat, vegetables to fit your taste. Possibilities are endless.

Supplies

A pot
A sieve
Oil
Coarse salt
Pepper corns
Kitchen scraps (stems, peels, leaves, fat...)
Fresh herbs, spices...

Note that all your kitchen scraps need to be edible!

Step 1: Gather Your Ingredients

Except if you're cooking a huge meal, you'll need to gather your ingredients gradually over the course of your daily cooking sessions. The best way to achieve that is to put them in a plastic bag in your freezer until you're ready to cook your broth.

Anything that is edible can be use. Be creative!

In that batch, I've used:

tomato stems
turnip stems (I've used the leaves in a soup)
onion peels (yes, that outside layer too)
carrot ends
zucchini ends
dried duck fat
ham fat
leek greens
radish stems (I've used the leaves in a soup)

Step 2: Heat the Fat

Pour a bit of oil (I used olive oil) in a big pot and heat it.
When it's hot, add all your fatty ingredients, coarse salt, and pepper corns.
Cook them until they are sizzling.

Step 3: Brown Your Veggies

Add all the veggies in the pot and brown them lightly.

Step 4: Cook the Broth

Cover your veggies with water. To add some flavor to your broth, you can add spices and herbs (here I used fresh thyme).

Put a lid on your pot and bring your broth to a boil. Then lower the temperature to let it simmer for at least 90 minutes.

Step 5: Remove the Veggies

Use a sieve to remove all the veggies, herbs, meat, and spices you've added in your broth.

If you are the lucky owner of a compost, you can feed it your kitchen scraps. If not, you can discard them. Note that all other ingredients can be retrieved to be eaten.