Hey Paulo,

Pinky G chords are definitely hard to get at first! I actually find my weakest and least agile finger to be my ring finger, so getting it onto that 3rd fret on the low E while keeping my pinky on the high E string is what would trip me up.

A fun and challenging exercise to work on your ring and pinky strength / coordination is try just playing patterns using only those two fingers. For instance, start on low E and play 3rd fret with ring, then 4th fret with pinky. Then go to A string. Etc. Up and down across the strings and frets. It's just an isolated finger exercise and not very musical, but that sort of targeted thing can help. I used to do that one years ago.

You could also just practice switching between that D chord and Pinky G over and over until it gets easier. It's an odd stretch and combination, though! So you'll have to be patient.

-Carl.