Setting up SSL correctly is not as simple as it looks. The basics: install the certificate and check it works. But out of the box, it might not work in all browsers, and your server might not be as secure as you think.
Qualys SSL Labs is a great (free) tool to check that your SSL certificate is installed and your server configured correctly. As well as checking the basics, it checks intermediate chaining issues, browser compatibility, and whether you are using any insecure ciphers on your server. For example, did you know that you should turn SSL off, and only use TLS?
It’s worth checking your web server encryption is encrypting properly, and not just providing the illusion of security.