Clean beats new. Repaired beats decorated.

With a photograph, not a purchase. People stop registering their own frontage after a year or two — ordinary perceptual habituation rather than carelessness — so photograph it straight on from the opposite pavement on an overcast day, and then look at the photograph rather than the house. Look at it small too: a thumbnail on a phone is how most people first encounter a property, and problems invisible from your own path are obvious at that size.

Cutting back overgrowth, then cleaning. Overgrowth is the single strongest visual signal that nobody is looking after a place, and it's free to fix. After that it's the door and frame, the glass, the drive, the bins, the gutters and the house number — mostly a weekend and some water, and it changes the photograph more than any purchase would. Careful with a pressure washer, though: too close or too high a pressure damages pointing and render.

Mostly the other way round. Dead plants, faded ornaments, an old satellite dish, tired hanging baskets and anything half-finished all subtract — and half-finished is worse than not started, because it reads as abandonment rather than as a house in progress. Once the removal and cleaning are done, the door is the highest-return surface there is, and one working light by it changes how the place reads all winter.

More than people expect, and it varies by country and local authority. Listed buildings and conservation areas frequently restrict doors, windows, boundary walls and even paint colours; the front of a property is often treated differently from the back; paving a front garden is regulated in some places because of surface water drainage; and a lease can restrict external alterations outright. One call to the local planning authority settles it, and doing the work first is the expensive order.

Nothing here can tell you, and be wary of anything that claims to. The percentage returns quoted for curb appeal projects generally come from surveys of estate agents' opinions rather than measured sale outcomes. What's defensible is narrower and still useful: a frontage that reads as neglected deters viewings and invites offers below asking, and most of fixing that costs very little.