Map Making 101

Not that I’ve found one, but I could really use a Dummy’s Guide to Making a Map. My novel, The Big Inch, is a WWII historical fiction and it utilizes real places in the city of Longview, Texas. Imaginary characters climb the stairs, stare off the rooftops, and gaze over lake surfaces in the very places that actual people walk every day. As I write the sequel to The Big Inch, called Harmon General, I’ve decided to add a map to the front of the new book–just as a reference for those who are curious about the context of the plot and locations mentioned. So, here are my questions. How much detail should go on the map? How accurate to mileage and longitudinal details does it need to be? And, if buildings sited in the 1940s no longer exist, how do I place them on the map? Do I create a walking map for readers to go to actual addresses, or just a loose approximation of location so that folks reading the book can visualize a general area?

You can see I have a problem that needs noodling, so if you have a suggestion for map creation, feel free to let me know.