How2TrainKaiju
Super Freak
It is very difficult for a first timer to obtain tickets to SDCC. The first batch of tickets go lottery style to people who attended 2015. The second batch of tickets go to everybody. Some people team up, since a single person can purchase more than one ticket. The tickets sell out in one hour or less.
Additionally, the hotels and even parking are sold via lottery.
I attended for 25 straight years, but could not get a regular badge. I could have gotten an exhibitor's badge, exhibitor hotel room, and parking. Exhibitors are not allowed to purchase some of the exclusives. At SDCC, it is who you know. I collect old comics, and honestly, there are not that many comic book dealers there. SDCC is full of cosplay and flippers.
You could try NYCC. There are many more things to do in New York than San Diego. NYCC is not as big in terms of exhibits, but attendance rivals SDCC.
Good luck!
Second everything said here. Pre-registration, an early registration for those who attended the last Con, is randomized and limited to a fraction of total badges. Getting in my first year was all luck. I got 5 days and a hotel next door. Boy, did that sure warp my idea of how difficult it could be. Every year was more and more frustrating. This year, I wound up not getting a single ticket during pre-reg. I was denied time off from work before open reg, but who knows. There are no guarantees. It used to be about fast connection and getting in first, but now they put everyone into a waiting room. Refresh, if anything, hurts your chances, and showing up to the site early means squat. All you can do is stay positive and try.