I'm an experienced guitar player, and I'm finally getting around to spending some time self-studying the piano. I've been learning a few songs by ear, and I'm wondering how to go about properly playing the arpeggio/melody combination in this tune that starts at about 0:20. It's a descending D minor-C major-Bb major-A minor arpeggio. I'm assuming the way it's supposed to be played is 5-2-1 with the left hand and then bringing the 3rd finger over to hit the high 3rd of the chord? Unfortunately, I've found that doing this while playing a melody in addition is at the limits of my abilities. Is there an optimal way for a beginner to practice this type of piece to "get up to speed"?
First, isn't that D minor, C major, Bb (without third), A minor?
In addition to practicing slowly, a good way (in general) to practice is to practice hands separately until they can do their own thing well and only then start playing them together. Also try practicing just a single measure over and over again. When you can play every measure separately start practicing connecting them. This applies to both the hands separate and hands together phase.
Now there are lots of ways to finger these arpeggios. You could try to play some of the notes with the right hand but it might be a bit tricky with the melody (maybe even impossible, I didn't actually try it). Here are some ways to finger the arpeggios which suit my hand, each with their own strengths and weaknesses:
Of course you can play one arpeggio with a fingering from (1) and another with one from (2) and so on, and you can modify these; I just tried to group them according to some common idea.