Today I went to get oil change for my car and realized I had my flight bag in the back . I couldn't take the whole bag and decided to take only my logbook. I started to think how important that little book is to me. I have my first logbook from 1983(eek that was a long time ago). Recently, I have flown with a gentlemen that had his first logbook from the 1960s. It is something you cherish and is precious beyond the fact that it logs your flights. It is truly a record of your passion for flying.
FAR 61.51 outlines what needs to be logged and how to log it. Briefly, you need to log anything that will be checked for example...training required for a license/rating and time for currency. As for how to log it, modern logbooks have all of the blank spots you will need, but you could keep your records in a spiral notebook (as long as you follow the outline in FAR 61.51).
As I was writing this a member at our club had his car broken into and all of his flight supplies were stolen, to include his logbook. He offered an excellent way to keep a back-up record and that was to take a digital picture of each page - genius! Easy, cheap and a copy.
fun log book with spaces for journal entries
all kinds of log books serious pilot logbooks