This is a great question, and one we get asked a lot!
Below is a list of things that CAN affect your approvals:
Your attendance percentage
When you submitted your request
The comment you leave when submitting your request
Your profile strength (how complete it is)
How often you attend a show
Ticket demand for a show
Keeping reserved/available tickets to other 1iota events in your account (read this FAQ entry for more info)
Things that typically do NOT affect ticket approvals:
The number of tickets you've requested
The number of requests you've submitted
The number of tickets/requests you've deleted
Past available tickets you've never reserved
Whether you have confirmed your email address yet (NOTE-- you will not be able to RESERVE your tickets until you have)
Remember, tickets are processed in the order they are received, based on the above factors, and production's needs.