Very lovely designs! As @Blizzei mentioned, you should definitely get into the habit of using showcases instead of sending the actual templates. Design theft/copying is a huge problem and keeping your templates to yourself is a good preventative measure.
Here’s my own piece of advice: Find a shading method that would go well with shirts like that. I did notice the seams, but the rest of the clothing does look quite plain. Look up some tutorials on YouTube, and keep practicing!
Also, once you do learn to shade, after you shade one shirt I would copy the layer with the shading on it and save it as another image. That way you can re-use the shading and not have to do it every time!
I hope this feedback helped!