First of all.... Have you applied to have a Stand in the event? That'll be the most important thing 
, usually, for Cons you'll first have to apply for their Artist Alley / Independent artist corner, which they'll announce in their socials and you'll have to fill a form.
If you get accepted then.
The most important would be knowing that JUST in case, to have fanart in your Merch. I know that You're supossedly not allowed to make fanart in these kind of events due to copyright laws and such (Despite you're not making more than 1000 items or being a mass seller that presents a problem to companies, IPs) but at least on my experience in Cons, if you have only your own artwork and on top of that you're not a regular that other regular attendants already know about at least a tiny bit, people will likely pass by you most of the time, so some merch from the popular thing of the moment may help slow down people and take a second to check your stuff.
I believe that in Comic-Cons, people already know and are into comics and that there are Independent sections for artists, but in the Events I went, most don't know this and simply think you're another Commercial Seller who sells less known items, and not that you made these 
A lot of people that want to promote their comics on Cons, usually have these things:
- Merch, obviously (Be it posters, stickers, mini fanzines, or buttons)
- They draw live, be it taking pencil commissions or simply drawing their own stuff
- Plotters / Standies with the Cover of your comic and some information, like socials, or what the thingy is about.
- Standing up, and try to make conversation. Yes, being charismatic and social is a top priority as well, avoid being that artist that is on their Stand without looking at anyone except their canvas, as well try to smile or have relaxed expression, since some artists tend to have a grumpy face when they're focused and some people may avoid you thinking that you're in a bad mood (Despite you're not!)
- Make sure to have contact info to easily hand to others, those are good too. For example, this was mine... probably 6 years ago
Edit: I forgot to add
I don't know how other people's experience is but mine always had independent artist VERY VERY far away from the main events, and only Editorial and Commercial Stands were allowed to stay near the Stage or the main areas where people gathered. So try to team up with other Artist Alley members if this ends up being your case. You can collab with other creators and make paper banners to tape to walls in order to catch people's attention so they go to the Independent section.
That being said, try informing yourself about the area where you'll be, if it'll be outside, or in a closed area, to have the essentials. Water, weights for your stuff so it doesn't fly away, sun-screen, an umbrella, and similar. Also,a nice tablecloth is good to keep your stuff clean and more presentable, try to use plain white fabric so your stuff stands out
