"Keep your eyes on the stars and your feet on the ground"
This a good quote for all aspiring writers to have. Never let loose your dreams of becoming a published author. But become a published author wisely. Do your homework on which agent you want and even if they accept your genre. Your dream agent might have taken your romance novel in the past but decide they want mystery thrillers presently. Just when you think you're finished...edit & rewrite. Repeat this over and over. Get sick of reading your novel and take a break from it for a month. Then take it in with fresh eyes. Writing is all about doing the extra leg work to get your novel as polished as possible in order snatch an agent with query letter (which is an entirely different process.)