It depends of what you're looking for.
If you are not going for anything in particular, i suggest you to try a bit of everything.
- These cons have shops and spectacles as their main, so you will definitely end looking what the shops have to offer and stopping in one spectacle or two (i suggest you to look the schedule, maybe you find something that gives you curiosity). Some of these are done by fans around the certain theme they are talking about and usually interacts with the public. It could be fun
- Also, cons have always cool cosplayers. Don't forget the camera!
- Talents. If you like art and writing, these are full of great talents. Some are just exposing their works while others could be found there to take a commision or give a signature (you may find even a famous talent).
- Finally, there are always profesional spectacles and some contests worth to be watch. As I said before, take a look at the schedule to not lose them
It's late and I can't think properly, so that will be all. Just remember having fun and... take money. You won't get out of there without something, that's for sure
And one more thing, careful with the food there, prices there for food are not in dollars, euros or cents... but eyes, kidneis and other internal organs.