At school, French kids use Bescherelle or Bled to learn French.
Bescherelle is indeed a great reference even when you are a native, this is the French version of the book
I don't think there's another way to learn French conjugations other than by rote/drills. After all, its the way French kids learn them. The ultimate reference for French conjugations is Le Bescherelle; each French family has at least one (or at least used to). It's also available as an app.
You can also find conjugation exercises online, and they're not just for learners of French as a second language:
* Générateur d'exercices de conjugaison
* Site du Nouvel Observateur
* Bien écrire.org