There are certainly methods to improve memory to remember dates, peoples names, stories and other details .... the methods I have seen rely on our memory being best at remembering visual and unusual things, so for example you can visualise placing a list of things in different rooms in a place you are familiar with (like your house), then as you later mentally walk through your house you will "remember" the items in your list in the order you placed them in your house.
Not sure about the other things you mentioned, except things like time of day, rest, diet and distractions can affect them.