As a hobbyist writer, my best advice would be,first lengthen your portfolio. You can opt for self-publishing in the beginning or getting published in magazines.
Based on the feedback, polish your work. After you've built a strong portfolio, write an eye-catching proposal. It should include a catchy title, a summary of your book, a detailed chapter-by-chapter breakdown, target audience, and a sample chapter.
To increase your chances to be noticed, network at literary events or online platforms to grab attention of editors who could guide you to the next step. You can also hire a literary agent who can help you navigate the process.