Want to be a novelist? So do I. But how to go about it...

These are just my personal opinions, so if you don't think they'll help just ignore them. :D I think you should write something you feel comfortable with. Don't write scifi or romance if you don't feel like you can do it as good as you should. Write about characters that you love, let the story grow as much as you like it to. Don't worry too much about "what will sell" or how things "should" be. I assume you want to write a good novel, not something that feels carbon copied. Maybe start of with a couple of short stories, to get your author voice down. Writing is not like working in a factory, it's a creative process that needs to be allowed to take time. You will keep on growing as a writer the more you work, just like painters need to paint in order to get better. Good luck, I hope this was a little bit useful at least!