Oh god. I did like 3 different cons in one month back in 2016. That was a bad idea, especially when I hadn't really did cons before. Also I had no stands or banners. I had a decent amount of stuff but the table itself looked amateurish and boring. Really regret how much I paid for them all.
So yeah, I recommend getting that banner. And some comic stands so people actually see your stuff. Oh and if you can, get some wearable merch. People are more likely to buy shirts and hats then comics (but don't let that discourage you! Make comics!).
I'm probably not going to do cons for a long time but best of luck to you anyway.