Ensure your site is secured with SSL certificate & protected from malware.
Ensure your website is updated with fresh content & latest news.
Ensure your site has fast loading time & remove the unnecessary
In term of website health, the best is if you can do the maintenance monthly. Your website is your store. But in an online world. Take care always.
Always keep a proper maintaining on renewal for domain, hosting & SSL certificate. This need to be maintained yearly.