When it comes to sample prep, the most important thing to remember is this—garbage in, garbage out. No matter how good the microscope and no matter how good the microscoper, a bad sample will always be bad. The effort in microscopy should not be in image editing; it should be in sample prep.
I have kept this chapter slightly generic, as you could dedicate an entire book to sample prep techniques alone. The best advice for the microscoper is to (a) research your sample and how other scientists have prepared it and (b) experiment! Take your time with sample prep—it is the key to good microscopy.