TeamViewer provides a script called teamviewerd.sysv available in /opt/teamviewer/tv_bin/script. Here's an excerpt:

#!/bin/bash

#

# /etc/init.d/teamviewerd

#

# chkconfig: 2345 95 05

# description: daemon for TeamViewer

#

# processname: teamviewerd

# config: /etc/teamviewer/global.conf

# pidfile: /var/run/teamviewerd.pid



### BEGIN INIT INFO

# Provides:          teamviewerd

# Default-Start:     2 3 4 5

# Default-Stop:      0 1 6

# Required-Start:    $all

# Required-Stop:     $local_fs $network $named

# Short-Description: TeamViewer remote control daemon

# Description:       TeamViewer remote control daemon

### END INIT INFO

All you need to do is make sure this script runs on startup. Making sure of this is relatively simple, just copy it to /etc/init.d like so:

cd /opt/teamviewer/tv_bin/script

sudo cp teamviewerd.sysv /etc/init.d/

Don't forget to make the script non-writable to anyone but the owner!

sudo chmod 755 /etc/init.d/teamviewerd.sysv

Then run

sudo update-rc.d teamviewerd.sysv defaults

The service will now start automatically with each boot. If you don't feel like rebooting, you can start the service manually with:

sudo service teamviewerd.sysv start

2019 EDIT: This answer was written in 2013. Since then, systemd has arrived in force and is normally used for constructing services that start upon boot. For instructions on how to achieve this in systemd instead, please see this question: How do I run a single command at startup using systemd?