I started writing short stories. I tried writing horror, mystery, science fiction. I joined a little critique group here in town and ran my stories past them. After about three years, I tackled my first novel, Subterranean. It took me 11 months to write. ↗
Discover the time of day when you write best, and write then. For me it's about 7 am to noon. For other people it's overnight. Try not to do anything other than write between those times. ↗