Another way is to just ignore that. You can finish all the major plot points, but leave all the smaller things for readers to imagine after an open ending.
About doing it carefully... ekhm, jokes aside, I think it's not about doing it carefully, but about finding a point where your story has no major plot points open. All the smaller things can be completed in side stories or just left as they are.
The thing is, in a way you need to leave a lot of things without conclusions. Ending every little plot point in a story seems unnatural, because it just doesn't happen in real life, save for specific rare situations. New things crop up all the time.
If you ask me, you should just end a major plot point, slap a good conclusion of it, not of the whole story, and if you want no one will stop you from writing a second part where the small things are adressed. That worked for me, at least. I initially wanted to end my story in around 30 chapters, but I was really hyped to write it, so I wrote a part 1 ending in chapter 36 where a large plot thingy was finished, and continued writing.
I will obviously need to end it sometime, but that's the concern for future me. If you really want to end your story though, you'll probably end up better if you end it, but don't stop writing it. Creative juices are not something you can afford to waste, and writing for yourself is good.