4 tablespoons of flour
4 tablespoons of butter 
2-3 cups of stock (beef, chicken, fish, vegetable ) or water preferably stock though 

In a sauce pot melt your butter and add flour whisk till it become a paste cook until light brown or golden brown for darker gravy and beef stock cook just a bit pass golden brown. Season the paste with salt and pepper any thing else you want, the more you make it and depending on the dish you will know how to season it.

Slowly whisk In the liquid I always eye this part some dishes you may want a thicker gravy others a thinner just depends on the fisher just watch the thickness as you add the liquid if it's to thick at more stock or water to thin bring to simmer or boil and cook off the liquid