Make sure your passwords are good enough.
Get approximate IP details.
Take an IP and try to look for the domain/host associated with it.
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Get all the HTTP headers that an URL returns for a typical GET request.
Get all possible details about an SSL certificate.
Check for 301 & 302 redirects of a specific URL. It will check for up to 10 redirects.