Keep a basic log of weight sets and reps achieved, i always make a note of how hard the set(s) were and put a + if I felt I handled the weight comfatably so I know to move up next time and a - if it was a struggle and I need to stick at that weight for another workout.
For diet I dont keep a log, but eat the same 6 days out of the week so I know what im consuming without a log