Any critique on my designs?

I have been trying to sell designs at Redbubble for some time now, but it isn't going great. I have been on Redbubble since July, and gotten one sale (which was on the first day).

I don't know if it is against the rules to post this here; but here is my most recent design: http://ift.tt/1OdaR31

(http://ift.tt/1KU1GSK) - For the rest of my designs

I have done many different types of designs to see what sells and what doesn't. The only one that has been sold is a Polygon penguin one.

I didn't really expect to sell much, I am a teenager that just started out with graphic design half a year ago.

But if anyone more experienced (with either Redbubble or graphic design in general) can look over some of my designs and give me some tips, that would be a huge help.

Lastly sorry is the grammer is bad, not my first language

Great design resource

100 Things Every Designer Needs to Know About People (Voices That Matter) Submitted October 04, 2015 at 04:01PM by Helhol http://ift.tt/1OdaTrL