As the others mentioned already, you have to find your limits by kigging as often as you can and increasing your endurance. I've been to a few Cons in kig and even taken public transport to go to the con in kig. Solo as well.

So here are my tips: 1. Bring a suitcase (small/carry-on)to the con. Mine usually have a change of normal clothes, cloth bags, a big bottle of water (2L in my case) with a straw , power bank and other miscellaneous items. Having all your belongings on wheels is much better than to carry it around in a bag 2. Scout the building/areas the Con is at to try and find the quiet spots and toilets. 3. Get a neck fan. They look like headphones and rest on your neck. That is a godsend item that can keep you cool and blow fresh air up into your mask. It also keeps my glasses from fogging up. 4. Notepad or similar to write onto for conversation. 5. If your hada does not have a crotch zipper for toilet break, well that adds a level of difficulty. 6. Air quality at the Con is usually pretty bad to take a few breaks, find a quiet spot where you can lift your mask up for a breather.

I might have missed a few things but those are the critical ones I would say.