Some homes can be fairly nondescript, so clear house numbers are essential. This DIY idea ticks three boxes: it's cheap, quick and reusable. If you're looking for an easy project to decorate your fence or porch this might be fun to try.
House numbers made from nails! You can buy black nails but if you've got time you could paint old nails any colour you like. Start with a stencil, some nails, a hammer and see where you end up.
(image source: papernstitch)
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Make sure they're readable, in case an ambulance (or whoever) ever needs to find your house.
When I am going to someone's house that I have never been before, I am always surprised to see how many street numbers I can't read from the street. It makes me nervous for them in case of a fire.
This article gave me a bunch of ideas.