It's gonna be really hard. I work at a hosting company and our staff has to work constantly to make sure people's servers get taken off of spam blacklists, or IP blocks of ours need to get removed, etc. There's a lot of stuff to navigate out there, basically kludges that have been put in place because email is just such a terrible, insecure system.
I'm sure if you're willing to put in the effort you can do it. But from my point of view, I'd probably just get a managed VPS with a hosting company who will take care of all the headaches of dealing with spam filters for me. They can be had pretty cheaply and the money is well worth it if you get good support.
To be fair, your viewpoint is very different from OP's. Where OP is trying to run a one-person mail server, you probably manage thousands of IP addresses and VPSes, which makes for a lot of abuse and effort on keeping reputation, and is an entirely different ballpark.
Therefore I'd advise OP to keep at it, not just switch to a hosting company. Also for the learning experience, though that is secondary.
The spam filtering companies do make mistakes sometimes. Sometimes someone is sending out legitimate mail but it's a new IP sending a bunch of mail and they err on the side of caution.
Or sometimes your IP will just get caught when a spam company decides to spam flag an entire block of IPs.
I think if OP keeps at it, they will find that it's not worth the hassle and for a very reasonable amount of money they could have just had a personal email server where someone else deals with the headaches.
Of course, again, I work for a hosting company so I may be biased here but I'd probably be saying the same thing even if I didn't.
I'm sure if you're willing to put in the effort you can do it. But from my point of view, I'd probably just get a managed VPS with a hosting company who will take care of all the headaches of dealing with spam filters for me. They can be had pretty cheaply and the money is well worth it if you get good support.