The fastest way to waste money on a refurbishment is to decorate before the boring work is done. Fabric first, then services, then finishes — in that order — means nothing gets opened back up after it has been painted.
Fabric first
Roof, gutters, damp, windows and any structural movement come before anything cosmetic. These are the items that damage finished work if left.
Services second
Rewiring, heating and plumbing all involve chasing walls and lifting floors. Getting them done before plaster and flooring avoids paying for the same surfaces twice.
Plaster and joinery
Skim coats, stud walls, doors, skirtings and architraves come next, sequenced so plaster dries properly before decorators start.
Finishes last
Decoration, flooring, tiling and sanitaryware are the visible spend, and they are also the easiest place to phase over time if the budget is tight.