Not all states require Notaries to keep journals or records of their notarizations, but it's always a good idea regardless of state law. If, instead, you think a filing system or a cabinet filled with loose papers is an adequate substitute for a bound journal, remember the last time you misplaced or lost an important document normally stored in such a manner.
A good notarial record generally includes the signer's name, address and signature as well as the date, method of identification use, type of document, type of notarization and any additional information. A properly bound notarial journal keeps records in chronological order and makes it easier to show that the records are complete, proper and have not been doctored. All of that protects you by demonstrating reasonable care was used. In addition, you can keep the journal with you when traveling to an assignment or easily lock it away.
Keeping files of miscellaneous loose notes about a notarization isn't a reliable or secure record keeping system.