You’ve just completed a temp assignment, and the boss is too busy to write you a reference. They say that you can write it yourself, and they’ll sign. Where do you start? Take what you do, insert adjectives to describe how well you do it, and hey presto! And if your boss has given any feedback (i.e. you're just so organised, I really appreciate that about you), then incorporate that into it. Take time to write it well, checking spelling and all that, since you are getting the chance to actually ensure that what goes into your reference letter makes you look the best you can.