write about what you like, if you ever daydream write down what you dream. if you like mystery books, read a bunch, use them as examples and write a spectacular story. (you can do with any genre) i am writing a mystery, with love in it, i LOVE mystery and love stories, so i read alot and I use writing techniques, mashed up ideas (along with mine) and so far I am on my 10 chapter. i have been writing it for a couple months now, sometimes I can write 2 or 3 chapters in a couple weeks, but this past month I haven't written any. i got writers block, so if you get it, don't think about your book, just look around you for a while and something will inspire you. :-)
P.S. Sorry for how much I wrote.