Some personal preferences and rules I like to live by :
Leggings are not pants - They should not be worn as pants - its not a good look on any body shape thin or fat.
Sacks are Sacks! - They don't do anything for any shape , they mighty be comfy and fashionable but they make all women look larger.
Beige Fishnets don't hide cellulite - they just make more mess and fuss around your legs.
Just because it come in your size does not mean you need to wear it! - I can't tell you how many women don't seem to understand this point.
Dress to suit your shape, show off curves (not wrap them in spandex) accent your positives and hide those bits you don't wish the world to see.
Remember in the end this is just my opinion, wear what you feel amazing in and what truly is you.