Break the thigh and leg bones to expose the marrow, that's where the flavor will come from.
Do skim the nasty stuff that rises to the surface within the first hour of simmering. It won't hurt you but it does make the stock cloudy and unappetizin. If there is a huge layer of fat, take part of it off. If there is very little fat, leave it and consider adding a glug of very dry white wine* to the stock, fat and alcohol both carry flavor.
For a very plain stock, season with roughly chopped onion, celery, and carrot. My go to for herbs is thyme, whole peppercorns, and bay. If you are planning to use it for something like Italian wedding soup, add some garlic cloves and use basil and bay as your herbs. Or just play around and suit yourself.
Oh, and crowd the stock pan, IMO a stock gets better the more stuff that toies in inrelation to the water since I can always water down a stock that's too strong for a light soup but reducing it gets rid of too much of the aromatic ciomponents.
*I usually keep a very dry vermouth on hand for this. It's generally inexpensive, widely available, and works.