Flow – look at how each area flows to the next. Ensure there is a good route to outside & enough space to do so. You don’t want an obstacle course to get from one area to the next – flow also means enough space around furniture for ease of movement.
Compromises – can you make do with a Euro laundry to create more space in the living area? Are good sized bedrooms more important than a huge bathroom or 2nd living? Being smart about choices can often work better than trying to have ‘everything’ and the spaces not working so well as a whole.
Furniture – mark furniture out to scale on a floor plan & move it around. Make sure furniture is the right size for the space. Try different configurations to see how best to use the space. This also helps with;-
Windows – marking out furniture allows you to work out window sizes, heights & where they should be on a wall. Allow your main seating to look out a window and not face a TV on a wall!
Kitchens – have the fridge on the end so you’re not having to go right into the kitchen to grab a drink. Make sure the walk in pantry is functional – plenty of open shelving, benches for prep & an extra sink if you have the space.