I look for current entering the bays or lakes from the marsh. It also helps to know the area like shell reefs good banks etc. I do not follow birds they noisy and occasionally [censored] on ya
The first thing I look for is if the lake has any artificial fish attractors. The second thing I try to do is look for structure. Even if its not explicitly marked on the map, you can look at contours to figure out the humps and holes.