Hello, over here for small inverted triangle diversion, thank you for the link MissScatterbrain not seen that before. It has helped me understand why some things work and others don't for me, some of it I put down to being petite (I am 5'2"ish) but now I think it is about shape.
Good things - A-line dresses, skater style dresses, turning up my skinnies to show some ankle (good with ballet slippers & pumps) as the turn-up widens me a bit there and stops me looking too carrot shaped (I knew this worked, but had NO idea why - instantly looks better), straight clean lines, contrast down the middle of an outfit, funky /statement shoes, no fussy necklines, volume on bottom half, necklaces to be weighted in middle (like single pendant) to draw eye inwards rather than rounded style, detail at ip level e.g. side ties to tops. tailoring and fitted clothes.
Bad things - fussiness on shoulders (e.g epallettes, cap sleeves, shoulder pads, detail on bust area), extra volume on top (e.g. layering), scarves (always looked daft on me), shapeless clothes (the leggings / tunic type combo has to be well fitted, i do better with tights, casual frock & boots)
Specifically on cardis, I struggle with these, they have to be really neat rather than waterfally.
That is a bit of a brain dump! I picked out this little number from Matalan (I was there randomly which waiting for car repair) that fits all the "rules" and I have been hoovering up compliments like crazy at work
. It looks 5x more than the 20 quid i splashed out 
www.matalan.co.uk/womens/shop-by-category/dresses/s2531588/monochrome-flippy-dress