Part of a song I'm working on is like a calypso but I wonder if anyone could help me on a good chord progression. The main one I have now is G6, Bb augmented, d 6/4, Bb augmented.

I'd just google other calypso songs or look at other sheet music of calypso songs and see what they do for chords. Most calypso pieces I've played tend to have 2 groups of chords that stick together, eg. a Bb to a D augmented 11 and then down to say a G and an Eb augmented. Most of the songs I've played favour perfect intervals, even perfects unison's. If you're still at school or university ask a music teacher. They're be sure to have some idea; if not I'm positive they'd have some resources or information to help you.

The key thing is to always keep the root note of the chord; calypso music also features "decoration" notes in the chords such as added 6th's, 11th's and 12th's. Hope that helps.