New to Lolita: Petticoat Help!

[afinedenouement.livejournal.com]

I'm fairly new to lolita and want to finally get a coord together, but I'm still really struggling with telling whether or not a dress needs an A-line or bell shape petticoat. I know that some people recommend drawing lines to better see the shape, but I'm still struggling. Any tips? Also, what type of petticoat would you recommend for Angelic Pretty's Marine Kingdom JSK? As I own this and desperately want to wear it. Thank you! c: Oh! And any recommendations for a coord would be greatly appreciated too (: