I used to cook more than the amount I will need, because I can freeze the leftovers and eat them days later without any problem. The time it takes depends on the sort of beans and how fresh they are, in a regular pot is approximately 3 hours high-medium heat, in a pressure cooker, it will take 45 min at the most.

So, add 1 1/2 litters of water in your pot, and when it is boiling add all the ingredients. They will be ready when the skin is soft.

Note:
* Some people think that to cook beans with salt make them tough and hard, my experience is that they are more delicious if you cook them with salt.

If you are cooking black beans, I recommend to add a sprig of epazote, it gives a nice taste to this sort of beans.