I am just beginning to learn about diodes and I was wondering if there are any tips to making the correct guess for the diode model. For our class, we use a model that consists of four regions instead of the simple on/off model. basically to figure out what the diode is doing, we insert the model we guess and solve to see if there is a contradiction. This becomes annoying fast.. So what are your tips for picking the correct region for the diode?