Measure every time I am with someone new. You would be amazed at the notations, and some of the pictures, I have in my book! Often I measure again with someone I have been with before. I use a plastic sewing tape to measure, along the top, from base to tip. Measure the circumference at the head, behind the head, middle, and base. I make the notes in my book and also how they were and what it was like and how much they could do and anything unique like very small balls or very huge balls or how they cum if it is special. Big cummers, small cummers, men who shoot long ropes or cum huge amounts or men who can cum and stay hard and keep going, that sort of thing. If a man is a 3 or 4 minute man that gets put down too or if he lasts and lasts and fucks like a stud. I don't use any rating system like stars or numbers or whatever but just use very descriptive notes to keep track and remind me so I know what to expect. I update my book too so it is current with all the information about them. I use a spiral ring notebook so I have space to write whatever I like.
Of course, I also have their phone numbers and address in my book too! LOL