Aries: Take them out for food or something fun, it will take their mind off the problem or why they're sad
Taurus: Let them be for a while, then offer to just keep them company
Gemini: Talk to them and listen to what they have to say, they will appreciate having someone to talk to
Cancer: Hug them and make them laugh, try and share their frustration or what ever they are feeling, it will make them feel better knowing someone agrees
Leo: Take their mind off the problem by talking about something they're really passionate about
Virgo: If they are annoyed or sad, try and relate to their problems or agree with them, if they want to be left alone, leave them alone, they mean it
Libra: Make them laugh and be optimistic, tell them it will get better, but not in an annoying way
Scorpio: Let them vent to you, but not be pushy trying to cheer them up, sometimes they need to be left alone
Sagittarius: Change the subject to something they like, they don't usually like it when people try and cheer them up, they don't like to feel babied
Capricorn: Be calm in the way you approach them, they don't really like to tell people their problems so don't ask them whats wrong, just be there incase they need you
Aquarius: Take them outside or do something exciting, ask them if they want to talk and if they don't then just chill with them
Pisces: Prompt them to talk about what's making them upset, they will probably feel better once they get it out, be there to listen and be accepting