Forewarning: never say “I will never have a stash.” Given enough time, you will, so just give in to it from the get-go.
People will share free yarn with you. Remember to pass the favor on to others. It really is enjoyable.
Fear not: mix yarns when the mood strikes. I have taken yarn that I’d never wear and mixed it with a staple from my stash, only to turn out some beautiful fabric!