Help with fitting/shape

I love this new dress! And it is easy! And has contrast! And a v-neck. I might actually get it done while it is still in season . . . The challenge is that I usually can't wear "shift" style dresses off the rack - they always look terrible so I never sew them. I tend to be a little more rectangular in shape without the perk of being tall, leggy and athletic, so this type of shape usually doesn't work. Any advice on how to fit this type of shape?