When talking to readers who do not write, the question of how an author creates characters is often raised.
I am quite fortunate in that I don't often have problems visualizing them. I get the hair and eye colour, their body type even before I have named them; I write out a timeline for them and create their birthday. Using astrological signs is one way of determining their strengths and weaknesses which is often an indication of how the conflict in the story might develop. If they have siblings can also affect their character depending on where they come in the lineup. A firstborn, for instance, is often an A-type personality.
The one thing that often causes an 'oh, yeah', kind of look is when I say I listen to my characters and go where they take me. But, if you are the author, I'm asked, how that can be? Don't you just have them do this or that and move them around like pieces on a chessboard? Well, no. That would lead to creating a cast of cardboard characters, so I do not ignore what they tell me. All of my characters are very different. Emmaline in His Dark Enchantress and Juliana in His Ocean Vixen, are both pretty feisty, outside the box kind of gals. Olivia, in His Unexpected Muse, is quite the opposite. She has reasons for being quiet and shy and I found it much more of a challenge to tell her story.
I love each of my leading ladies. They have made me laugh, given me headaches, surprised me in some of the things they have done but never, ever, bored me. I hope that comes across in my writing and that my readers enjoy my characters as much as I do.