Cosmo,
Things will click for you much better if you understand all the aspects of what you are doing, before you begin.
A plumb mast, as Babadem stated, is critically important.
Your longitude - the longitude coordinate of your location - defines what the nearest true south satellite should be. The ultimate purpose of aiming at the nearest true-south satellite is so that you can set your dish elevation to the highest point on the satellite arc. This would be to aim at the satellite that is at the top of the arc from your reference point.
Other factors are involved, such as the east to west (azimuth positioning) of the entire assembly and the latitude adjustment of the motor.
Having a receiver with a very responsive signal meter and having that receiver programmed with the nearest true south satellite and a known, consistantly broadcasting signal (TP) is necessary. With this, you can more easily position the dish elevation and motor azimuth to dial in on the signal.
Note that I state "nearest" true south satellite. Your site's longitude coordinate may not match up perfectly with a satellite that has a really strong signal that you can detect with your specific equipment. In such cases, you should merely dial into the NEAREST satellite to true south (utilizing the signal response from your receiver's signal meter). This satellite may happen to be imperfectly aligned according to what satellite position is at the top of the arc from your position or reference point. This will generate some minor errors, but with patience and practice, you can compensate for this error later through finer tuning to other known satellite signals.
My methods may seem very intricate and lengthy, but every step you take is the foundation for the next step. If you know and understand which steps should come first, and you take those steps methodically and accurately, then things will fall into place all the way.
If you know and understand what you are doing and why as you go, then aligning a motorized dish system should take you ten to fifteen minutes to have it tracking reasonably well.
Getting the system to track immaculately requires experimentation based upon the signal response from the satellites available to the specific area. You might have to sacrifice some of the signal quality from one satellite or one transponder in order to pull up the signal from another.
Hence, the more information you have in the back of your mind, the easier the process will become. You will be doing many steps subconsciously and almost immediately.
I hope this helps you and that it gives you a greater confidence for your project.
RADAR