Keep it neat. You can never have too much storage in a family bathroom. Shelves can look untidy very quickly so opt for cabinets with doors that can be closed to contain everything out of sight.
Decide whether or not you want shower valves to be exposed or concealed. Exposed shower valves work well in a modern country scheme and are also easier to install. But if you want a super-sleek look, a fixed rainwater shower head with concealed pipework can’t