Well, once you are done sanding and have cleaned the dust off, don’t forget to tape the doorframe and floor with some masking tape, leave it there once primer dries, then put your topcoat on, might want to “feather” the edge between new paint and old paint so there’s no hard line between the two, wait for that to be touch dry and THEN remove the masking tape. Much easier than trying to clean up paint drips and spatters after the fact.