What preparation means
Washing down surfaces, filling and sanding, caulking gaps at trim, and priming anything bare, patched or glossy. In this climate add one more: if a wall has ever been damp, it gets a stain-blocking primer or the mark comes back through, sometimes months later.
Sheen, and why it matters here
Flat hides imperfections and cannot be scrubbed. Eggshell and satin are the sensible default for living space in a humid house because they wipe clean. Bathrooms and kitchens want something with genuine moisture resistance. High gloss on trim shows every flaw in the woodwork beneath.
What interior painting cannot fix
A wall that is still wet. Fresh paint over active moisture blisters, and a stain that keeps coming back through a blocker is telling you the source has not been dealt with. In this climate that is usually a window seal, a roof detail or a shower behind the wall. The EPA treats persistent damp as a mould question rather than a decorating one, and so do we.
Timing
Paint after ceilings and before flooring, unless the flooring is going down first for a reason. Doing it out of order means masking a finished floor, which costs more than it saves.