I've been here less than 2 months but I thought I knew most of the important day-to-day things I should do, but just today I learned that if you power down too much and your SP goes to 0 you get locked out of the system, and you have to get someone else to transfer some SBD or SP to you.
Live and learn :)
SP is your stake in the platform and even though not much is needed for bandwidth, many don't realise 'some' is needed. with zero, you can't make a transaction at all :)