Three things, and being straight about them early makes the whole project easier. A realistic budget range — we can design to a number, but not to one nobody has said out loud, and the earlier that number is honest, the fewer redesigns it costs later. Decisions on selections made at the points the schedule actually needs them, because a kitchen waiting on a cabinet choice is a kitchen not being built, and a crew standing idle is a schedule slipping regardless of how well it was planned. And a single decision-maker where possible — projects with two people giving different instructions cost more and take longer, every time, because the crew ends up building twice or waiting for an answer neither of you has agreed on yet.