Fun and Whimsical -> this will be your direction of style.
Candy Corn is your main idea. I would suggest start with one single idea, before bringing in other things. Harvest as much element as you can from the candy corn.

Looking at the candy corn shirt and pants. Tell me do they look fun and whimsical?
I think they look kinda plain... it is just candy corn print on it... just like other tshirts with printed images or message. What fun is that?
As for the pants, the colour division may be fun... but straight and tidy division is... boring. Your shirt's candy corn print at least have the charm of random candy corn in different angles, like rain of candy corn.

Now, what I mean by extracting candy corn ELEMENTS. Observe the candy corn closely, what makes it a candy corn.
1. the colours. orange, yellow, white. Which you got right in the pants.
2. It is triangle! in 2D. Don't stop here, what it means by triangle? pointed, slant and angled lines.
3. in 3D, it would be like a flattened cone. So it does have some kind of curve.

You definitely have the colours right. Now is the matter of making it FUN!
From number 2, slant, pointed and angled lines.
Your pants, instead of a straight horizontal division... make it slant! simple change like that makes a lot of difference. You may even try uneven lengths. The pants do not need to end in straight cut, it can end in an angle.

Same concept to the shape. You can have a asymmetry shirt... with a huuuuuge candy corn shape dangle in slant. Imagine the pointed bit on one side of the shoulder, and the rest of it drape to the other side...
You can have a under shirt in it too.

Don't worry about skills, if you are worry about shading, then make your clothes tight fit. This is a contest! It seems like idea/design comes first? At least in my opinion anyway. I would surely scream if someone won with a plain orange t shirt... design~ design~ design~