Maximizing simplicity is the only guaranteed way to minimize software maintenance. Other techniques exist, but are situational. No complex system will be cheaper to maintain than a simple one that meets the same goals.
‘Simple’, pedantically, means ‘not composed of parts’. However! Whatever system you are working on may already be a part of a whole. Your output should reduce the number and size of parts over all, not just in your own project domain.
I’ve started asking myself, “does this add the least amount of new code?” A system in isolation may be quite simple, but if it duplicates existing functionality, it has increased complexity. The ideal change is subtractive, reducing the total amount of code: by collapsing features together, removing configuration, or merging overlapping components.
Better to put your configuration in version control you already understand, than introduce a remote discovery server. Better to use the crufty RPC library you already have, than introduce a new one with a handy feature—unless you entirely replace the old one.
Beware the daughter that aspires not to the throne of her mother.