What everyone else has said is spot-on...

The first Con in our state happened Summer of 2015--and lucky for me--was going on about 15 miles from where I live. And, even luckier still, Dean was a guest...
Having never been to a Con before, I went pretty clueless to the whole thing. But, regardless, I had a wonderful time.
A few odds and ends:
-See if there's a Question & Answer session going on at any point during the event. Dean was holding one on Sunday, but not the day before, Saturday. That gave me the basis of exactly when--date and time of day--I was going to attend.
-If there is a Q&A, get there early so you have a good seat. They openned doors for that specific 'area' about a half hour prior, if I remember right.
Dean's Q&A was about 45 minutes--a well-known radio personality interviewed him. It was awesome!
Kinda in the same vain with timing...
-Pay pretty close attention to when the Autographs and the Photo Ops are going on.
For the Con around here, on Sunday when I attended, there was an Autograph session that lasted probably 45 minutes. Then there was the Q&A a bit afterwards. Then maybe an hour later, there was another Autograph session. The afternoon finished with the Photo Op. I went into the Con knowing I wanted to (potentially) do all three, and planned my day around those timeframes.
Also:
-If you are getting an Autograph, decide if you are going to buy something there, or bring something of your own. They had pictures for sale--basic shots, lots of Superman shots. But, if it was possible, I wanted an autograph on an old article about L&C that I had always loved. It was no problem--and ended up being a great talking point during my autograph timeframe...
Have fun--you'll have a 'Super' time

...
Laura