I would do it the same as chicken stock.
beef bones
2-3 carrots
2 stalks of celery
2 onions
1 bay leaf
6 peppercorns
sprig of parsley, thyme, marjoram and/or oregano
I would roast the bones 1st for 30mins or so (450F)
then add to pan with rest of ingredients and boil for 3-5hrs removing the scum as needed
I never add salt to stocks and only add it once you have made the soup (near the end). You can always add more salt if needed, but you can never remove it