I'm full of questions today!! This one is: would it matter what book you published first if you're not a writer who has a very specialised output? For instance, if you wrote horror stories, and more romantic horror (or even something wildly different like chick lit and westerns), did both equally well, and got something published, would it then affect readers' opinion of you? Or, more relevant to my current wonderings, if you self-published a (for example) romantic book and then pitched a horror to a publisher, would they just see you as a good writer - or just a good writer of romance, and be reluctant to look at anything else? If you wanted to be known as someone who would write a particular thing, even if you wrote and are proud of something in a different genre, would you try and publish that first, or would the chronology merge together into a big picture in a publisher's eyes??
A lot of it is about marketing - and the fact that some publishers do only deal with horror or romance. The more specialised a genre, the better the publishers know how to market that, and only that. if you signed with publishers who dealt specifically in horror, they'd be at a bit of a loss if the next thing you sent them was a romance. If you go for a more general publisher, though, they might not know how to approach marketing horror. Swings and roundabouts, I think people say. I'm thinking I'll probably avoid the issue by publishing romances/realism under one name, and my fantasy novels under another. Then I can hope I don't p-off a publishers by going to someone else. Even among the fantasy I write a huge variety of different types of fantasy, from kids to pretty R-rated stuff, so... Yeah. Not sure what will happen there.
Sometimes writers use different or multiple pen names for their different writing. The one that comes to my mind for using a large number of names is Eleanor Hibbert who wrote as Jean Plaidy, Victoria Holt, and Philippa Carr, Eleanor Burford, Elbur Ford, Kathleen Kellow, Anne Percival, and Ellalice Tate. Her genre and style was a bit different under each name. I think a reader may expect a certain type of genre to be associated with a particular author--but worry about that after you have two books accepted for publishing.
...first of all, it couldn't, unless your name had become so widely known for the the first genre you were published in, that they'd recognize it... and i don't see why it would 'affect' readers opinion negatively... it would more likely make them curious enough to want to see how you do in other genres, thus helping book sales... you should never tell agents/publishers you query that you'd self-published anyway... but if they should know somehow, it could definitely make them not bother with anything else you wrote, since they generally consider having been self-published a sign that your writing wasn't good enough to interest paying houses... this makes little sense... can't tell exactly what you mean... and you're putting the cart miles before the horse, in any case... write something good enough to be published by a paying press first, get it published and then tackle the question about changing genres...