On the following link you can find a complete tutorial well structured which will help you to start speerunning this game.

Unfortunately this is now in french, but I hope soon that we could find a place to host a complete translation in english.

https://www.squarepalace.com/secret-of-mana-speedrun-tutoriel/secret-of-mana-remake-tutoriel-pour-le-speedrun-du-jeu-en-2018