If you're writing a novel or longer work, you may need some organization to keep up with all of the details. You don't want your hero to have brown eyes on page 5 and blue ones on page 58. Readers pay attention to details.

Index Cards
For my current manuscript and writing project, I made an index card for each character. I listed physical descriptions, likes, dislikes, and the full name. I added details as I worked on the manuscript.

Mapping - Relationship Diagrams
When I was teaching, we used to use mapping or relationship diagrams to help students brainstorm ideas. I use this at my day job when I'm facilitating brainstorming meetings.

Write the character's name in the middle of your page. I usually use paper, but you can use a posterboard or a whiteboard. Draw a circle around the name. Then write the next character's name and circle it. Draw a line between the two circles and write the details of the relationship next to the line.

I use this method too when I'm brainstorming the action of a chapter or a series of chapter. Sometimes, I'll draw a flowchart for a scene too.

Get out the markers or crayons. You can color-code items. Don't be afraid to scratch out write over. Draw lines and show all the connections.