> Actually getting SPF, DKIM and DMARC right and having a domain with a 0 spam score will still land you in the spam directory.
This little bit of wisdom gets passed around all the time, but it's actually not true. You can send email from a brand new domain to Google and Microsoft and whoever just fine. What you can't do is send email from a brand new domain, and a brand new email server--or an email server on a VPS, or an email server on a residential IP. Residential IP blocks are almost completely blocked, because of unsecured devices being used to send spam, and VPS blocks have the same problem. You can get around this by using a mail relay, or building your domains reputation on a server that already has a good reputation.
> or an email server on a VPS, or an email server on a residential IP
So what options are left for a self-hoster. Colo?
Find a host that cares about their reputation. It can be hard to know who responds to abuse reports, but if they mention it in their TOS that's a positive. Also, many hosts block outbound port 25 by default now; that's a positive sign as well.
The more effort you have to put in to use them to send mail, the more likely spammers don't use them, and the more likely their ip space has a positive or at least non-negative reputation for sending mail.
Get a business-grade connection from your ISP. Make sure they give you a static IP from their business side, and check its reputation before you set up email. If it has a bad reputation, make the ISP give you a different one.