This game is a GREAT place to start because it really doesn't require any crazy skills. I recommend looking through some of the runs so you can get a feel for the general route, but most of the speedrunning is just having good input time for the minigames and not wandering too far off route. I'd especially check out the Snow White chapter runs, because there's an easy cutscene skip during it! Certain minigames, like the first part of "Tune Up the Band" in Ariel 3, have the same inputs every time, so you can memorize those, too, to help cut down a little time.

Overall, the game isn't heavy on any viable glitches or exploits, so it's a lot of just... playing the game as intended, lol. Good luck!