Ditto. Started 20 years ago with one service I wanted. Complicated it a little more every time some new use case or interesting trinket came up, and now it's the most complicated network in the neighborhood. Weekend projects once a year add up.
If you have the resources, experiment with new services on a completely different server than everything else. The testing-production model exists for a reason: backups are good, but restoring everything is a pain in the ass.
I also like to keep a text editor open and paste everything I'm doing, as I do it, into that window. Clean it up a little, and you've got documentation for when you eventually have to change/fix it.