Other resources
NIST Small Business Corner
Very helpful guidelines and tips specifically focused on small business security
FCC Small Business Tips
A readable list of tips that small businesses can take to protect themselves as recommended by the Federal Communications Commission, a government organization
CIS SME Companion Guide
A guide to security targeting specifically SMEs (small and medium-sized enterprises) based on CIS controls that covers the most common risks for small businesses and how to mitigate them.
NIST SP 800-53 Revision 4
NIST is an industry leader for cybersecurity controls that provides a detailed framework for various parts of security, including incident response, access control, and configuration management.
ISO 27001
This paid document (currently £110.00) is the international standard for security, information management, and privacy. Has a certification program if you are interested in obtaining an international cybersecurity certification.