We have had some really colourful sky recently
I bought a plain t-shirt and stitched on some flowers. The t-shirt is actually a lot darker and a different colour than the photo looks, it's like a really dark jade. Instructions below.
I drew a sketch on paper, then I put some stabiliser on top [something like stitch and tear although I think mine was regular stitching stabiliser]. As you can see through the stabiliser it is possible to copy the design onto it, I used a pen.
Pin the stabiliser to the right side of the t-shirt where you want the placement, then embroider - I used back stitch.
Then carefully tear off the stabiliser. Job done.