The top of your dress Thana is beautiful. Just watch the edges to be smooth and make the shade a darker version of the main colour instead of just a gray. Maybe copy the shade of a real dress to know where to shade.
Critique on the Red Dress The first thing I would do is make the dress much MUCH less saturated and bright. Bright, neon colors are kind of a turn off because it can hurt the eyes, and it clashes with the low saturated, neutral colors on the accents.
Also, I don't see any highlights, so try adding a few! It would also be a good idea to add more wrinkles coming from the belt and more shadow opacity variety. Oh, and maybe you could add a few highlights on the belt to add depth?
One last thing; On the leaves, try to fill the color in completely. The insides of the leaves are a little messily colored in..