It's everyone's dream as a guitarrist to play like a certain someone that inspires us. Can be a solo guitarrist like Paul Gilbert or Steve Vai, or a band guitarrist like Syu from Galneryus.
Gabriel said that he started studying Iron Maiden a long time ago, and that's kinda my question...How to study a band's theory: The steps so to speak, for me I usually have the common issue of needing a list by order of doing, for me to know what to give priority at the beginning...

Cheers
Filipe

I understand your question,but I do not have the answer. Maybe someone will help out here? Rock on bud.

What I do when trying to study a bands theory is to listen for similarities between songs.
For example, with Iron Maiden:

- They often use gallop rhythms for the backing guitars and bass.

- The chord sequence often has I, VI, VII in it. For example, if they were in the key of E Minor, they would use E - C - D. Gabriels lesson on Iron Maiden actually has that chord sequence I think

- They often use harmonies in the main riff. These are usually "diatonic thirds". Again, many Maiden songs have this - Listen to The Trooper, Hallowed be thy name, Deja Vu to see what I mean. Gabriel again uses a third harmony in his lesson

I think these are some of the characteristics of Iron Maiden, and this is why the Iron Maiden songs sound like they do, and why the Iron Maiden lessons sound like they do. Of course, you can apply this to loads of bands, just try and see what similar things they have in their songs

Jomathan has a good approach, you should listen to the song and try to find out what is going on, what are the rhythm guitars playing (galloping parts? open chords? unusual tunings? speed parts?...), what are the lead guitars playing (shred stuff? harmony leads? is there only a main solo or are there leads between the verses too? are there even leads during vocal parts? any unusual scales?) and you can of course apply all this to bass, vocals, drums and keyboards too. Like this you get an idea what the band is using to create their songs and their style and you can use this information of course to reproduce this style.

I agree with the rest, and suggest you start from learning the songs of your favorite band. Find out in what key the song is, and what is played on top of that key all the time. Interesting things to follow are guitar lead lines, and bass lines and vocal lines as well. Try to see what is are often note choices in those songs, and see if there are any key changes as well. You should know your theory before you start this analyze of course.