There are actually more than 5 things, but these are at the top and important for you to think about before approaching a designer.
Purpose and Target Audience
What is the purpose of your site? Making a lot of money is certainly a good goal, but if that's your only reason, then you need to think about the site's purpose. What do you want it to accomplish? What do you want visitors to do while they are there? How do you want it help convey your brand, products, books, artwork, etc.? What are the long-term goals?
Who is your target audience? Millenials, stay-at-home parents, people who like to collect antiques or play video games? "Everyone" is not your target audience, so you need to narrow the focus. Doing so will help with both the website's purpose and your longer-term marketing plans.
The purpose of an author website is to showcase the author's books, but what else? Does the author want to sell books from their site, direct the visitor to a retailer, do they want a blog where they share updates or host other authors, and on and on.
For a small business, no matter the type, do you want visitors to simply learn about your business or services, or do you want them to take action? Book an appointment, fill out a questionnaire, follow you on social media, subscribe to a mailing list, and so on.
Break down all the things you want your site to accomplish, starting with the top 3-5 things, and then provide that information to your designer. It will help streamline their focus when they work on your site's layout.
Budget
This is a boring and uncomfortable topic for some people to discuss, but budget matters. You might love ABC website and want your site to look exactly like it, without realizing a site just like it would be thousands over your budget.
Be honest with yourself and your designer about your real budget. Don't forget to consider website hosting, purchasing a domain, email, and if your budget includes marketing, then you need to break those out and decide what your real budget is just for the website.
Your designer should be completely upfront about costs and what they can deliver within your set budget.
Your Timeline
Don't underestimate the time it takes to design a website. Some designers can get your project done in a week while other designers and more extensive projects require months.
Be honest about when you want to start and when you want the site live. Consider the time it will take for you to gather or create all the site content because you will need this before the project begins. For e-commerce sites, this includes product images, names, descriptions, pricing, plus return and shipping policies, payment options, etc.
You also need to account for realistic feedback turnaround times. You might think you'll be able to provide feedback to your designer the day after they send you the draft site to review, but this is rarely the case.
What You Like, and Don't
Never say "I'm good with anything," and then get upset when your designer selects orange as a color when you hate all shades of orange. Do not tell provide them with links to three sites that all look different and then they model the overall design after your least favorite of the samples.
Web designers aren't mind readers, so communication is essential.
Research other websites, and select your top two favorites. Decide what you like most and use that information to help inform the preferences you share with your designer. For example, perhaps you do like anything, but prefer not to have orange, red, or purple. Maybe you want earth tones, or only like two shades of blue. Perhaps you like a minimaist look with mostly whites and beige.
Your designer should provide you with a questionnaire so they know your preferences before the project begins.
Content
Before you contact a designer, make sure you have your content ready, or know what you need to create and gather.
This includes site copy, high-quality images, videos, etc. If you want your designer to source images and video for you (doesn't work for e-commerce products), then you need to let them know in advance as it will increase the quote due to tangible costs and time spent.
Does your site copy need work? Do you need help writing it, or does it need editing? These are important questions to consider as web designers do not often offer these additional services, and if they do, they are unlikely to be included in the cost of the website design.
Conclusion
Researching other sites, branding, content details, and more are also necessary, and your designer should be able to provide you with a list of everything they need from you in order to complete your website project.