Create a template to track your character's various bits of information. You'll need to know the basic physical traits, such as height, weight, physique, gender, age, hair and eye color, as well as things more specific to your character such as his or her powers, skills, place of birth, citizenship, home town, origin, history, motivation and personality type. Simply write each of these categories down the left margin of your paper, or in your word processing document. If there are other categories you'd like to include, feel free to do so.
Fill in the basic physical traits you have categorized in your template. This will create a good visual idea of your character's appearance.
Decide on what skills and/or powers your character will have. There are two fairly simple approaches to this. The first way is to simply decide what you'd enjoy seeing your character do, the second is to craft a fun origin and let that dictate the powers, skills, etc. If you character was given powers by an industrial accident, then the type of accident would determine the powers. If your character was infused with the DNA of an animal, then your character would take on the abilities of that animal. The sky is really the limit on this. Write these skills and powers in the template when done.
Fill in the more specific information on the template such as home town, citizenship, history, etc.
Create your character's origin, if you did not already do so in step three. Again, this can be dictated by the specific skills/powers you want to give your character, or it can be the springboard for the skills and powers.
Design an eye-catching costume. Early comic book superhero costumes were designed to be visually striking, even a little outrageous. Towards the end of the 20th century, costume trends moved more toward practical applications, trading garishly colored spandex and capes for custom-fitted leather with muted colors. Regardless of trends, however, this is your character, so he or she can look like anything you can imagine. Add the costume details to your template, so you, or someone else with art skills, can draw the character at a later date. You will need to detail footwear, lower body, waist, torso, arms, neck, head and any additional items or equipment. Include color and fabric type in the descriptions.
Create an arch enemy. A hero is only as good as his or her enemy is bad. So, once you have a well-rounded super hero, use this same procedure to create a villain. Give the pair a conflicting set of interests and you'll have a great character ready for a superhero story.