brother, not even all spanish speakers get the spanish subjunctive right... my girlfriend has this endearing affectation of using the conditional where normally you'd use the subjunctive, she'll say stuff like "si estaríamos allá" instead of "si estuvieramos allá".
"vaya a españa" is more like an imperative form... think of the subjunctive as something that happens in conditional constructions. you can just say "fuera a españa*", that's kinda meaningless and weird, but you can say "si yo fuera a españa". meaning if i were to go to spain. so like, "si yo fuera a españa me comería cuatro paellas" or something along those lines. <if i were to go to spain i'd eat four paellas>. whenever you could add in a 'were' or 'were to' or such construction in eng, you might want to use a subjunctive.
proper subjunctive usage is, i think, easier to get through intuition and a lot of learning than through study of the formal rules of grammar, though, so read read read listen listen listen is my recommendation.