Re: Important stuff!
A floatplan and someone at home who knows it as well.
The appropriate licenses and registration depending on local laws and regs.
An anchor with its own line is always good.
Other gear I try to keep compartmentalized by purpose. I run dry bags and totes nearly exclusively. In a tote I keep all of the survival stuff. First aid kit, gps, and other goodies applicable to the size of boat you are running. Then a cooler for food. Then whatever tackle/gear stowage you have.