Give your characters things that they want. Having established goals is a great way to drive the story and create storylines when you're running low on ideas. You don't want characters that seem perfect. This strikes readers as being unrealistic and boring. If you want people to really sympathize with your characters and root for them, give them flaws. They can be greedy, too talkative, rude, selfish, or not exactly smarter than your average bear. Give your characters backgrounds, interests, hobbies, and other things that show that they have actual lives. This makes them seem more real and relatable. Fight the cliches! Don't make your characters "normal" by comic standards. Give them individual and unique characteristics, and think of new and different ideas for your comic. Remember, your characters don't have to fall in love. Don't make a character for the sole purpose of being a love interest; make them realistic, and if a love story seems appropriate between two characters, let it develop in a realistic manner. Cliches aren't how people are, they are how people think they are supposed to be. You can help change this by making your characters behave like people do in the real world.

Summary:
Give them hopes and dreams. Give them flaws. Flesh out their lives. Fight cliches.