One of the major challenges of shooting with film then and now is shooting in manual mode. This is especially the case if you're shooting with a fully manual camera with no built-in light meter. So, you either have to get yourself a reliable handheld light meter or train yourself to "read" light so you can adjust your camera settings for the right exposure.
Thankfully, there's a neat printable guide -- let's call it a cheat sheet while we're at it -- that you can use as a paper "light meter" during your shoots. . thephoblographer.com