Hi mate! Randy was an amazing guitar player. He had classical background and created his own style combining the rocker style of classics like Jimmy Page with the roots of shred guitar. He took his classical etudes and influences and combined them with his own way of playing heavy metal and helped to create the neoclassical guitar playing style. He had a very tight technique that combined alternate picking, sweep picking, tapping and legato.
The best ways to understand and study a guitarist in following this steps:
- Listen to all his music.
- Read about his bio and influences.
- If you find a musician that influenced him very much, consider analyzing him too.
- Learn some of his most used licks. You can use youtube for this, just write Randy Roads licks and you get this:
LINK- Analyze his compositions. Learn the riffs, the chord progressions and see what typè of tonalities and combination of chords he uses during the songs and also during his solos.
- Learn some of his solos. Isolate the difficult parts and create variations for diary practice. Analyze what is happening there. (theory)
- Practice the solos over the backing tracks and try to create variations of the licks to make them of your own.
Those are the guidelines that I would use to analyze a guitarist. Sometimes you also can check their guitar clinics, but in this case I think that it's not possible. You can check his GMC lessons:
http://www.guitarmasterclass.net/ls/Randy-Rhoads-Style/http://www.guitarmasterclass.net/one-on-one/tapping-2/Let me know what you think and please count with me if you want my help /guidance to do it.