Read as much as you can, in whatever genre, for inspiration. Also, even without realizing it, most writing is somewhat autobiographical. Look to your own life, also in whatever genre, for ideas. It is, after all, what you know best. Not everybody can write well, so you might try out a few ideas or short writings with friends and family, before going all in. Find an editor and/or a book doctor, for another set of eyes. If you are fortunate to find a publisher, they will provide an editor, cover design, proof reading, and so on; but if you are self-publishing you need to hire that help.