This list is pace my recent reading of "Secrets of a Proper Lady," which was not quite up to snuff.
1. Start with the Arranged Marriage plot, and add the Mistaken Identity twist, so that your main characters are lying to each other from the start.
2. Add a bunch of secondary characters whose only purpose is to make difficulties for no purpose whatsoever, then make them complain about how unreasonable the main characters are being on all fronts.
3. Have your main characters fall in cowardly, cowardly love all while taking every opportunity not merely to support their ridiculous charades, but to actually make them exponentially worse.
4. Reference Shakespeare and his hidden-identity plays as much as possible, so people realize the author is smart and is Playing With Sources rather than just Fucking Around. Nobody will be reminded how great Shakespeare's romances are in comparison to this drivel -- I promise.
5. Keep increasing the financial stakes at dramatic moments just to make your main characters twist in the wind as much as possible. Who doesn't like reading endlessly about that?
6. Make the conclusion the least promising wedding scene in history. For instance, when at the end of the ceremony the vicar (clearly appalled) mentions snidely that a kiss is customary, by all means have the bride and heroine respond: "I would rather die."
7. This may be the most important point of all: Definitely add as an epilogue a first-person scene where the author is forced to debate the subject of her next romance with a bunch of her past characters. Extra points if you mention that previously one of your characters has faded away and out of existence from an excess of two-dimensionality.