Today's special is about character and conflict. I really don't think you can separate the two when it comes to your book. Different characters = different conflicts = different reactions to situations = different decisions = different actions.
When people say romances are "all alike," this is what they're not getting. The situations may fall into certain categories (marriage of convenience, for instance); however, it's the characters and their reactions and the backstory that causes those reactions and motivates their decisions that make each story unique.
So here are the links to my character/conflict worksheets intended for use in my workshops More Than Just A Pretty Face: Creating Unique and Interesting Characters and What Lies Beneath: Adding Layers to Your Characters and Conflict.
ETA: the links have been deleted.
Characters/External Conflict Worksheet
Character/Internal Conflict Worksheet
These aren't intended to be the last word in character development. Nor do you have to have answers to all of these questions when you start writing your book. Some may not need answers and I'm sure you can come up with plenty of questions for your characters on your own. These are just some things to think about, and may also come in handy if you're stuck.