Characters have to speak to your readers and fit with your story/genre. Part of the secret here is to think about who your readers are and would they relate to your characters. I use people or groups from my life. I sit and think about their characteristics and how they react to different situations. By adding speak, accent, mannerisms, dress, eating habits anything - will add value to your writing. Look at these photos and write about them. Think about people you know who might be like the people in these photos and use that information to help you. Use your life - use your feeling towards them and use your situations to add value .... Let me know how you get on and thanks for reading.