Generally, if I take a photo with a sophisticated camera (ahem, I have only one, the Pentax 67) then scanning is a breeze. I can do an entire roll of film in a couple of hours; one evening. With the lo-fi cameras, I spend more time first making a 'reality' scan of the image "as is", and then doing multiple variations of the same image through adjustments to each of the color channels in attempts to 'find' a better photo, more detail, or more character and soul. I may also increase or decrease the saturation, or convert it to black and white, and save all these versions for later comparison.
Pictured above is one of my recent scans. It was an image taken last month in a plastic camera with an attached polaroid back. The film was a black and white Polaroid type which expired 9 years ago, and while I should have shot this as a long exposure, because it was very early morning, very cloudy, and I had a dark filter over the lens, I forgot. All this resulted in an underexposed photo with barely any image, as you can see.
It doesn't end there, however. All's not lost. There's nothing to lose in trying to pull something out of these types of images when scanning. Sometimes I find my best images this way. Lightening it, manipulating the color channels (I always scan as 24bit color, even if it's black and white) and other adjustments will cause distortions, and exaggeration of the film emulsion's aberrations, and the dust particles, but all that adds to the character. The following are three of the 5 or so variations I made of the above photo: