One of the panels I went to at Norwescon was Writing in Other People's Universes. The topic didn't interest me too much, but it had Greg Cox, so I thought it might be somewhat entertaining, at least.
It was fascinating. The panelists went back and forth between detailing what it was like to write media tie-ins, and interesting anecdotes about particular books or books series that they or someone they knew wrote.
Some of the bits I recall are:
Publishers tend to go to the same authors over and over again. When doing tie-ins, the publishers have to deal with all kinds of wackiness from the rights holders. So they tend to go with an author that they've worked with before, so they know that they're not going to get grief from them, and that they'll meet the deadline.
There were lots of stories about the trials of novelizations. Apparently, they normally work from an advance copy of the script, and the novel has to be finished about 6 months before the movie comes out. But the movie can get changed a week before release. Sometimes there'll be an updated script that they aren't allowed access to, or a twist ending that they refuse to tell the author because it's proprietary.
Apparently, there's a new trend where they sometimes won't let the author have the script at all. The author has to come and read it in a locked room, with a guard present, and then go write the novelization from memory of a draft script.
There was some discussion of how to break into the field. One way not to do it is to write a story in a world you like and send it in. The publisher would have to go the rights holder, and start negotiating for the rights to print your novel. This never happens. The way it works is the other way around, the rights holder goes to the publisher and says, "We need 3 Whatever the Movie novels," and the publisher finds some author or authors they've worked with before.
The consensus seemed to be that the best way to break in is to write your own fiction, get known by various editors and publishers, and then happen to be around when there's a crisis and there's a novel that has to be done quickly and there's no-one else to do it. One of the panelists worked on the game, I think module design but I don't recall for sure, and when there was a tight deadline for a game novel and there was no-one else to do it, he got a shot at it. Another of the panelists got his break when someone else, 8 months in, cancelled out of a project, and there was only two months to get the novel out.
Then, once you get your break, their advice was always say yes, and always get it in by deadline. Earlier if possible. The consensus there seemed to be that reliability was the number one criterion.
Another way, particularly for an amateur or first-time author to break in, is the Strange New Worlds contest. If you get published in it, it means that several people in the Star Trek publishing industry will at least know who you are. It's open to new writers only (no more than two published short stories) so you'll be competing with other new writers, and not established professionals.