Gary has been helping people purchase a horse for many many years and with great success. There have been too many times to count when owners come to our facility to get training on a horse they have purchased but just can't handle. A good rule of thumb to follow is a green horse and a green rider do not mix. Having said that, a young horse with a nice temperment combined with professional training can work out well.
If you are a new horse owner with little experience, it would really benefit you to take lessons from a professional. These lessons help you to build a better relationship with your horse and with a better relationship comes more enjoyment.
We used to send every horse home with written instructions for the owner on the program they should follow. We did get away from doing that...why? Not sure, probably just lack of time on my part. However, we are putting that back into practice as it gives the owner something to always fall back on. You can always refer to it when things start going backwards. This allows you to always get back to square one when you get into trouble.
Gary keeps these programs pretty simple and he also includes a list of the suggested tack. For example, what type of bit works best for both the horse and rider. When the owner is comfortable with that program, they can then move forward and work on something new.