I honestly wouldn't bother too much with looking at scopes. Fresh ears can make a big difference and understanding your reference monitors is also very, very important.
However, the best way for a beginner to check a master is to take a recording of it and listen to it on as many different systems as possible and at many different volume levels. Play it in the car, play it on your phone, play it on a nice hi-fi, play it on some shitty headphones.
The point of a general master is to sound good on the widest range of devices. If you're doing a specialized release, your target might be different. For example, FLAC releases are generally aimed at audiophiles and so you can aim it more specifically at higher end audio systems and headphones.
Most of the time, you'll probably be making a wav/mp3/ogg for general use and therefor a very wide range of devices will be used to listen to your song.