I had quite a few things missing following this guide - see here:
e.g. if you don't copy in your old wp-config.php - all your users that have a login - will get a security breach warning or be logged out.
If you use ssl - which you should it will be even more complicated (impossible to use letsencrypt until the dns points a couple of days towards it and so on -- really a lot of hurdles. I'm working on it for 3 days now and still nowhere near going live.