everyone likes different things.. if u are writing only for fame then that is a bad reason to write in my opinion... you have to write what YOU would like to read and what YOU feel like writing. the only way you could have a chance at best-selling otherwise is if you ripped off popular authors, and i doubt that will work. Otherwise, try to avoid clichés... an original story (and good grammar) is always better. And if u need help about precise things in your novel, you can ask an editor or people online for advice as well.
good luck!