Following the guidance of http://patrakov.blogspot.co.uk/2011/01/writing-systemd-service-files.html it was fairly straightforward to use systemctl on Fedora 17 to start the tinc daemon on startup.
Create a new file /etc/systemd/system/tincd.service containing:
[Unit] Description=tinc vpn After=network.target [Service] Type=forking ExecStart=/usr/sbin/tincd -n network-name [Install] WantedBy=multi-user.target
Replacing network-name with the name of your network.
Then enable the service to run on startup
sudo systemctl enable tincd
If you’re using the default firewall note you also need to open port 5353 (listed as multicast DNS) to get avahi to work with tinc