Set up a vpn server (such as using ivpn to configure vpnd) on your home mac and connect securely to it when away from home. Don't do anything like screen sharing outside of the encrypted tunnel provided by the vpn. Also, if you don't have a static IP at home, set up a free domain name via a site like no-ip.com who also provide software that can keep the nameserver in sync whenever your home computer IP # changes.