After the SSL cert is installed,
1. Change all website links using HTTP to HTTPS.
(If you use relative links, no changes need to be made.)
Find all non-relative links in the website that go to pages, images, JavaScript, etc.
Change to relative link paths: If the link is “http://www.example.com/link” change it to: “/link”. Be sure the links start with a forward slash (“/”).
Test it out: Refresh your browser cache and click a link on the website.
2. Setup 301 redirects from HTTP to HTTPS
For Apache-based (Linux) websites, set up a redirect. Add this code to the top of the .htaccess file in your root folder:
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]
Then test thoroughly that your website is still functional and that any request made to your site is redirected to an HTTPS URL.