I am having trouble playing and memorizing the broken chords sequence:
Should I try and practice on each triplet individually? because when I try to think on it as a broken chord I often can not play it correctly. Any other tips will be welcomed.
There are a number of great ways to practice any given pattern. Taking the rhythmic skeleton of your passage, you can apply 3 different Duple-based patterns, each with two 16ths and an 8th. Modifying the rhythm of each triplet thusly helps to develop 3 overlapping schema for each possible way to group 3 notes. Note, it's better to think of these, not as three different rhythm patterns but as three different starting points for a rapid group of 3 notes.
The obvious thing to do next would be to add more notes.
In this case, you'll want to start to overlap, practicing the first triplet plus 2nd downbeat, then the 2nd triplet plus 3rd downbeat, and so on. This would continue on to 5 notes, 6 notes, and finally 7 notes, which would constitute two full triplets plus the following downbeat.
There are dozens of other ways to practice, but here is one more valuable way to approach your particular example.
Although the fingerings may not match, it is valuable to "flatten" each beat into a triad.
However, these particular arpeggiations are grouped into diads, so it's most helpful to flatten and organize them in that way.
Does this give you a few ideas to work with in this passage? I mocked these up quickly on my iPad so please forgive the incorrect enharmonic spellings used.
I would advise you to write out the song using numbers instead of the chord letters. Eg using 1 for the chord based on the first note of the key and up to 7 for the last note. I actually recommend using roman numerals as they look better than numbers.
1 = I 2 = II
that way you will much better be able to see what is going on with the chords changes