You should be aware that a number of people would be offended by having someone say "Hey!" to them; it is particularly rude to try to get a complete stranger's attention except in the most pressing circumstances with "hey!" (For example, any store clerk would be justified in being offended by being addressed with the words "Hey! how much is this belt?") As any number of mothers and schoolteachers have said to children who said hey!, "Hay is for horses."
As a synonym for "hello", it might be better to use "hi!" (which is pronounced in the same way as high) instead of "hey!"