How do you go about figuring how much oil to use for frying? Off the top of my head, I can think of a number of factors such as the type of food, how well you want to cook it, the type of oil, the size of the pan and how much food you are trying to cook. Which of these factors should I worry about the most and does anyone have any general rules for figuring out how much oil to use?
As you suggest, there are a number of factors, but the best rule of thumb I've found for pan-frying is to use just enough oil to cover the bottom of the pan by swirling it around. In general, you don't want puddles (you'll get splashed with hot oil), but if the pan isn't covered then your food might not get cooked evenly.
These days I mostly just eyeball it, and err on the generous side. Using slightly too much isn't likely to hurt your dish - unused oil just won't get absorbed - but using too little will result in under-cooked or inconsistently-cooked food and probably a lot of gunk stuck to the bottom of your pan. So if you're not sure, just add a little more than you think you absolutely need.