Don't fix what ain't broke

This is a very important life lesson. One that will save you a lot of work. If a certain system works like it should, unless you are going for a major optimization, just leave it alone.

Don't force a change in something that's already known to be dependent.

For example, don't build a fire pole in your house even if it will save you a bit of time going downstairs. That will definitely pose as a hazard in the long run.