Writing romantic suspense is like any other romance and should avoid a lot of backstory. It's important to develop that backstory when you do your character development, for you have to know your characters to know how they will react to certain situations. However, don't bore your readers with all this knowledge. A lot of new writers think it's important for their readers to know all about their heroine's past or they won't "get it." Wrong. Give your readers credit.
Look through your character profile and pick out things you can use to create a suspenseful scene. In FOXFIRE, my heroine, Grace, likes silk things. It's something I discovered in the character profile, but not important for the reader to know...or is it?
Here's how I used that in my book:
"...Grace opened her mailbox and removed a large brown envelope. Her name and address had been printed in neat block letters, but there was no return address. She studied it for a moment, wondering who had sent it...
(Okay, building a little suspense in those few sentences)
"Curiosity got the best of her and she pulled the strip to open the envelope. Peering inside she saw a silk ivory scarf."
(Aha, part of my backstory, but how does this become important? Read on.)
"Last night, Tyler had kissed her goodnight after walking her to the door. Could this be a present from him? He said that her skin looked and felt like silk. A rush of pleasure warmed her. No matter that she had fought against it, she was falling for Tyler. He made her feel beautiful, not outside, but inside where for so long she'd felt soiled."
(Anticipation and a little breather for the reader.)
"She lifted the silk to her cheek, closed her eyes, and rubbed its smoothness against her face..."
(Grace loves silk)
"Tiffany (Grace's Dog) sniffed at the paper that had fallen at Grace's feet. Grace stooped and picked it up. The words scorched her vision. Printed in block letters was a name that made the bile rise in her throat. Gracie Jo. Only one person had called her that--the man she'd been hiding from for three years--Max Clayton. She read the note again. Gracie Jo. I know you like silk. This is for you. A gift. Like old times. How did you like the roses? Wheren't they pretty? Such a vivid shade of red. The color of fresh blood."
Okay, now we have suspense. The villain has found her. Her world is now changed. The reader's expectations are now waiting for the confrontation which is a given.
Now, it's your turn. Go back into your characterization and pull out something about your character you can use to write a suspenseful scene.