How can I increase my sales on eBay

I am currently selling Yugioh decks, and I average about 1 sale a day which is about $20 profit.
I have other competitors as well, one is doing about the same as me and the other selling about 4-10 decks a day which is crazy. I made an instagram account to promote and its going okay, made a couple of sales from there. I want to be able to sell 2-4 consistent, anyone know any tip or tricks to get the ball rolling.