Play as Inferno.

Guys, I need your help. Today, I decided to play Heroes 5 for the first time (before that, I only played single-player) and I don't know any tactics or what units to recruit and for which heroes. So, I want to ask you: in what order should I build a castle, capture mines, which units should I buy, which heroes should I use to clear neutral creatures, and how should this happen? What skills should I develop for each hero, which schools of magic, and why, so that I don't just follow some scheme, but also understand why and why I'm developing exactly this way, exactly this hero, exactly in this situation.