Manuscript format is actually simple. Here's
a good link on that; it's visual as well as explained in writing. It's for a short story, but everything I've read says novel manuscripts are the same. At the very least, you want 1" margins all around, 12-pt Courier New (or another fixed font, one where every letter takes up the same amount of space), and double-spaced.
For this next part, please forgive me for telling you a bunch of stuff you probably already know:
Now, if you're talking about how to write the novel itself, that's harder. There are some great books out there on writing romances; I really suggest you check one out of the library. I had one years and years and years ago wherein an author explained her EXACT formula for a novel, but I've lost it and naturally don't remember the name of the book. It was insanely regimented though; she had exactly 20 pages for each chapter, for instance.
There are certain other conventions in romance novels. These days, the main characters have to have sex. And if it's an historical, with a presumably virginal heroine (hell, even if she's widowed), she must always be surprised by the size of his manhood, and wonder if it will even fit. (Usually manhood is used, sometimes cock, but never penis. Go figure.) Lately, it seems as if the hero must also pause to gaze admiringly at the heroine's vulva (but of course you never use that word). If the heroine has been married in the past, there must have been something wrong with that marriage, even if she was widowed. (Romance novels seem to all ascribe to that "one true love" theory.) Either it was loveless, her first husband was abusive, or somehow it is revealed to be less than what it seemed. The hero and heroine must have a misunderstanding, and while it is something that is easily resolved simply by talking, they cannot ever actually do that
. It seems that usually there is something that requires a physical separation of the couple at the center. The relationship is of course the central plot, but there has to be another one as well (it's no longer acceptable for Regencies to be comedies of manners, something I bemoan frequently). Bonus points if you can work in time travel and/or kilts. I am being somewhat facetious here, but only somewhat. You know most of this stuff if you regularly read romances. Personally, I'd kill for a good romance novel that broke some of the conventions.
More generically, you will have that other plot, which is built around some central conflict. Mysteries of some sort are quite common. Bonus points if the heroine's life is at risk (ok, really, bonus points if it's the hero, and the heroine DOESN'T stupidly wander into the bad guy's clutches in an attempt to save him). Of course the final denouement is going to be within a chapter of the end of the book, but before that you will have at least one, probably two or three setback(s). Where to wrap up the romance is up to you. I've read some romances where that part is settled 2/3 of the way into the novel.
I'll share my favorite resource again: Holly Lisle's Forward Motion
. She covers everything
. Plotting. Creating conflict. Creating characters. Writing scenes. You have most likely never heard of Holly Lisle, but she's published over thirty novels. Her World's Gate trilogy really should be required reading for anyone wanting to write urban fantasy. She manages to have a believable widow, a new romance without denigrating the first marriage, and a child who is actually a functional part of the story without being preternaturally wise.
I do some character creation beforehand, but I don't generally plot out the minutiae of various scenes.
I do not have a fill-in-the-blanks character sheet. I have a little bit of that at the top, along with a picture (in the case of my heroine, I found a model who had the right look in a book of crochet patterns; the hero comes from a recruiting ad
): I have the character's full name, nickname, DOB (& hometown), physical description, etc. Then I do some free-writing to get down what I know about the character.
I don't have anything against fill-in-the-blank character sheets. They can be really helpful if you don't know your character well.
Here's a character sheet for you, but I think Holly Lisle's is indispensable as well (because it gets into motivation):The Epiguide.com Fiction Writer's Character Chart
Hope something there was info you can use.