As a child of a mom who often nags me (though she prefers it not to be called that lol) I would say, try to give your kid/kids a little room to make their own mistakes. Unless it's something dangerous or important you're trying to get through to them about. Though I understand that my mom's nagging comes from a good place a lot of the time it just makes me frustrated and half of the time I was planning to do what she nagged me to do
before she even nagged me about it. It's not fun to feel like you're being babied (as I'm sure it's not fun to feel like a nag on your end
).
Just know when to pick your battles. If the kid/kids' room is a mess and they couldn't care less about cleaning it, fine. let it get dirty, hopefully they'll get tired of living in their filth and do something about it. If it's something of real importance, then just make it a point to bring it up to them once or twice maybe. Just so they know you're concerned, but don't try to force the issue, it could do more harm than good.
Good luck.