If you need to address a stranger, or get their attention for whatever reason, you should remember the following:

A

All strangers (except for children) should be addressed as Вы.

B

Women in general are Де́вушка! (Miss!) - unless this is obviously inappropriate.

C

Men in general are Молодо́й челове́к! (Young man!) unless, again, this is obviously inappropriate.

D

In those situations where В and С are inappropriate, simply use:

Прости́те, пожа́луйста...	Pardon me, please...
Бу́дьте добры́...	Be so kind...
Скажи́те, пожа́луйста...	Tell me, please...