If you just published your online website and you need to take the first step to make sure visitors can reach your website you can review my checklist below that I use for any new website I create.
A sitemap is a web page on your site that will help search engines find, crawl, and index all of your website’s content. Sitemaps are also explaining to search engines which pages on your site are most important. You might find ready made plugins or modules for your website that can help you to setup your sitemap XML file easily. Also, you can read more about Sitemap XML from here.
If you don't know it, Google Search Console is the most important tool that can help you track your website links on Google index. From there you can submit your Sitemap XML URL.
You need Google Analytics to track and analyze your website visitors.
It's important to establish your online presence on Twitter. First impressions count, and your profile on Twitter will help you keep connected with your visitors after they leave your website.
Crunchbase is having the innovative companies and the people behind them. It would be very great to have a profile for your business on Crunchbase.
The largest startup community is on AngelList website, it's very important to have a profile for your business on AngelList to help you gain credibility for your business.