I definitely keep a logbook, and I write down my workout ahead of time...just with the first weight to use and I up it from there depending on how I feel. When I get to my last set I see what weight I used and how many reps. Then I make sure to either use a heavier weight or go for more reps. If I can't do that then I do another set.
I don't know how you can lift without a logbook.
This has worked for me very well over the last 8 months since I've started training.