Plan everything extensively at the beginning
Whether you’re doing one room or the whole house, it really pays to be rigorous in your planning at the beginning—and that is a sentiment felt by most interior designers I’ve spoken to, too. I didn’t do this quite specifically enough, so there are areas in my house that should have a plug socket, but don’t, and others where it feels my radiator layouts could be better. I highly recommend printing out a floor plan of your house and marking where you want all the lights, plug sockets, radiators, etc, to go, and think about how you want to use each room. Where will the bed go? Are you going to incorporate built-in wardrobes? How will the doors open, and where should the light switches be for ease of use? These things sound small but they change how you live in your house, so they’re really worth considering.
Decide where you want to save and spend
When it comes to the decoration of a property, there is a balance to be struck. Of course, it depends on the budget you have left after you’ve (horrifyingly) spent most of the budget on plumbing, but I’ve come to the conclusion that it’s best to invest in some things—taps, specifically—and save on others. This bit is really up to you, but for me a good quality kitchen was key, but when it came to seating we bought an old (but excellent quality) B&B Italia sofa off eBay and got it reupholstered, saving us thousands of pounds.