Saddle height is one of the key components of bike fit. So, it's a great thing to work on if you want to feel comfortable on your bike but don't want to spend your money on a high end bike fit just.
If you want to do it yourself you are going to need a level, a tape measure, and a plumb line.
This video will show you how to do the Holmes method, the 'Inside Leg' method, or the Kops method. If you want to give it a shot it looks like the 'Inside Leg' method may be a bit more accurate.
Although I think it is still best to get fitted by a reputable shop, knowing these methods will help a lot in a pinch.