All advice / Planning and cost
Protect performance first
Start with the parts that determine whether the room works: a sound layout, proper preparation, waterproofing, drainage, ventilation and safe electrical planning.
Decorative upgrades are easier to reconsider later. Poor preparation is harder and more disruptive to correct after the finishes are installed.
Then prioritise daily use
Give priority to the shower, toilet, vanity, storage and lighting choices you will use every day. Consider access, cleaning and the way the household actually moves through the room.
A smaller list of well-considered choices can be more useful than a long list of features that compete for space.
Make the trade-offs visible
Ask your renovator to show how each change affects scope, price and timing. Keep approved changes in writing.
This turns a limited budget into a sequence of decisions rather than a last-minute compromise.