Black Skimmers are one of my favorite birds to photograph. They are also quite a challenge due to their speed and agility. Yet with these three quick tips below I've been able to get consistently good results. Of course with this type of photography, your ratio of "keepers" will increase with more practice.
Quick Tip 1: Use a very fast shutter speed for birds in flight. This was shot at 1/1250.
Quick Tip 2: Use AI Servo (AF-C) mode to track and maintain focus as the birds flies past.
Quick Tip 3: Use one active AF point, the center. It's typically the most sensitive, and locks onto the subject faster than the outer points.
At first, you may find it easier to practice with slightly slower birds, like seagulls, or geese. These can also be fun to photograph and will help polish your technique for your next round of action photography. Enjoy!