I keep a cover page for each section (airframe, engine, avionics, prop) and I keep them in the log book. Besides making an entry in the log book, I track all the SBs on this form. It has columns for various categories of information like compliance, dates, recurrence, etc. It makes it easy to see at a glance all the SBs and whether they apply and when they were completed. I maintain them excel. I can email you a copy if you'd like.