For most barbers it'll just be easier to just show the photos rather than try and explain exactly what you want. You'll want them to be a higher resolution than the ones here, but get photos of the front, sides, back and maybe the top if possible that best represent what you want.

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Also if its your first time getting your hair cut in a certain style then I think its worth booking in with a "fancier" barber who will do a 10-15 minute consultation before the haircut and go slow with it if you don't mind spending the extra money, rather than going to a chain store that gets lots of customers and might rush you a bit. Then take photos of your hair after the cut and use it as reference photos when you go back to a normal barber for maintenance cuts