Read the types of books you find most interesting to determine which kind of historical novel best suits your taste. There is a dramatic difference between a medieval war novel and a regency romance.
Consult primary research materials to make sure you have your facts straight. Readers of historical fiction have little tolerance for writers who don't do their homework.
Visit the locales you plan to write about if at all possible. Often, the physical reality of a setting holds a quality impossible to convey if it merely remains a name on a map to the writer.
Surround yourself with artifacts of the age you are writing about. Perhaps a ship's wheel or barometer is exactly the inspiration you need to feel the salt spray in your teeth in order to render the travail of a North Atlantic crossing.
Consider carefully whether your novel will benefit more from a first or third person narrator. While a first person story will make the voice more immediate, it can also stray into anachronistic verbiage that might put your reader off.
Ensure the pace of your historical novel is enough to keep the reader turning the pages. Often, writers become so immersed in telling the history of their story that they fail to keep the narrative brisk and entertaining.
Attend book signing events in historically accurate garb. Many people are attracted to living historians at historical society functions and renaissance fairs.
Reach out to Internet book circles to promote your book once it's published. Participating in these discussions without always plugging your book is a way to increase grass roots interest.
Contact publishers that specialize in historical novels of the type you have written, remembering that some will prefer series novels while others will be more attracted to stories that stand alone.