What I do is cool down in the fridge over night, skim the solidified fat, and then freeze. I'll often get a portion of the skimmed stock and reduce it to a demi glace before freezing, often just to save space in the freezer, since I try to make at least a gallon at a time.
Yeah, that's generally my approach. Definitely don't freeze it in freezer bags though, as they stick together making it difficult to use it in the intended amounts.
