Try to learn as much as you can about the fighters in the featured bouts. If you have the time, go to the weigh-in and pre-fight press conferences and open workouts. Try to get a feel for each guy's styles.
If you can, get their official records from Fightfax (I don't know their web site and it will cost you to get their records, but they're the most accurate source in the business. Boxrec.com is a good free source, but not quite as accurate) because it's not unusual for promoters to lie about records, especially those of the "opponents," the guys who are paid to come in and face the local guys. Above all, make sure you can somehow independently verify a fighter's record before reporting it.
In the fight itself, just try to focus on the flow of the action, who landed the harder blows and when. Make note of any cuts or marks on a fighter and what caused them and any knockdowns and what punch caused them.
Many commissions supply the media with copies of the master scoresheet after the featured bouts so you can see how each judge scored each round. Remember, the judges are watching 4, 6, 8, 10 or 12 one-round fights so one really big round by one fighter might not be enough to outweigh his opponent's dominance in the other 11.
To learn about scoring, pick up a booklet called You be the Boxing Judge by Tom Kaczmarek.
Here's the link. I have the booklet but it's also available in DVD and VHS.
http://www.tvboxingjudge.com/