I guess it kind of depends on what you wanna play. For any style the best thing to learn is your major and minor pentatonic scales up and down the neck especially if you wanna play lead. For metal i would learn your minor scales first(harmonic, melodic). For blues lkearn major and your blues scale which is basically two notes added on to the pentatonic scale. Once you learn your majors and your minors, learn arpeggios first....get familiar with those cause those are generally what you use when you play.