Hey y'all, I attended the virtual winter SCBWI conference in 2021 and an in-person regional illustrators conference in 2022 where I participated in the portfolio showcase--your experience in NY may be different, but hopefully this helps.
spark notes version:
Most of all you need something good to write with and something good to take notes on. Bring something to take pictures of slides. It can be an intense learning experience, especially if you have a specific growth road block you have hit, because you really come ready to learn then, and the people come ready to teach.
I highly recommend preparing some questions to start conversations with others (mine was "so, do you have any pro tip for these conferences?" the one person I asked had never been either and was only beginning to think about illustrating) The second part of that is to get their contact information and actually reach out to the people you met after the conference. I didn't do that last half, but if you do you can make really valuable friendships of all sorts.
the portfolio showcase was a bunch of tables with the portfolios laid out with corresponding business/post cards. there were a lot of fancy ones that kinda didn't work... and a few store-bought ones. I would recommend functionality above all else, and if you can have an introduction of some sort with a picture at the beginning that would be phenomenal. It might not be obvious, but people will not recognize you as the creator of such amazing art unless they can put a face to the name and the style. It will make it more likely that people will remember you.
(p.s. for my portfolio I just used regular page protectors in a regular t-prong folder something like this and taped an intro with a photo on the inside cover. none of my art fell out, which is more than I can say for some portfolios)
now the big debate... post or business cards? both? We were only allowed one or the other when I participated in the portfolio showcase. I decided to do postcards so I could print a whole image and write an introduction on the back. When I got there I saw that the postcards people had brought didn't have much writing on them (or at least would be send-able and usable for someone) and the postcards and business cards didn't always seem to match up with the portfolio (like they just brought what they had already made, which kinda threw me off when I was trying to associate the people attached to the portfolios and cards correctly in my mind (also most didn't have photo or introduction, so it was rough))
So I would recommend doing whichever one makes most sense for you, but preferably make something new that is updated and promotional (and will make you recognizable and memorable)
last thought, after the conference put together a lesson based on what you learned to synthesize and remember better those lessons, and share it with some friends! it will be a great resource for you and a great exercise. I would really like an update on what y'all learned! I'll DM you maybe hee hee we can swap notes (my notes from the other conferences, yours from this one)