'useless' tip : give a name for your design/item. It will make you yourself feel the importance of CONQUERING it.
May not work for everyone. XD But more for my convenience to call it.

Green dress.
DESIGN : State your aim and idea. I caught the keyword wind breezy flow. Seeing how... 'plain' it is, you can consider adding some detail. If you don't have other design element, then you HAVE to do such a good job on the 'wind breezy flow'. Which I see, pretty... flat at the moment.
SHAPE : What Mariaria did was right, find reference. I start out with reference, if not MAKE your own. Curtain, bedsheet, any cloth. Observe how they overlap each other.
1. That being said, currently, your skirt hem seemed to be a 'slant' dress. As in one side shorter and one side longer. Not that it is bad, but if that is not your intention then it have to be fix.
2. I find it even you have the 'pleat' in same width, it is hard to control the exact width it falls at the end, so it is not likely they are in the same size of curve.
3. That comes to, understand your fabric. I know you have this 'wind breezy', the same velocity of wind act differently on... a canvas and a silk.
SHADE : WHERE is your light source? Or more precise, where is Menewsha's light source? Look at the faceless base, the light spot indicating that the base is facing the light at the upper corner.
1. The shading at the folds shows like the light come from right directly on top.
2. Unless the plaid is fix on the waist, or else the fold lines should have varying lengths.

Two Tone Shirt
DESIGN : Simple. Good. Better start simple and easy before attempting a monster. You certainly can consider more designs. Basic is fine too.
SHAPE : Since it is a tight fit, following the shape is correct.
1. You may consider thicken the collar line as it is quite... slim.
SHADE : Menewsha's palette is rather inconsistent, I prefer the palette with good contrast instead of the soft ones.
Pink is a colour that is so bright to see the shade difference.
1. As they said, too many dithering, it makes the surface look noisy and pokey.
2. Outer line could use more shading.
3. For the middle one, I think you could have mis-shaded the curve line at the breast. Suppose to be white, now is pink, resulting a strange shape when zoom in.
4. The hem fold currently... it loooks like something is poking underneath. O__O
You have the shading on both side, making a fold out quite visible, to the point that it is too stand out to be a gentle fold.