Mastering the Equipment
This is pretty straight forward. If you don't know how to under-ride an exposure, change the ISO setting & aperture, change the image resolution setting, etc., then you're going to have a tough time in the field when it's critical. It was the dead of winter when I first got my digiscoping equipment and the best subjects to practice on were backyard birds. There were cardinals, chickadees and juncos that made excellent subjects. Heck, I even practiced on House Sparrows. What does it matter, right? What you're doing is practicing at this point. When you practice enough to nail down how the equipment responds you will reduce unwelcomed miscues occurring in the field. In a moment of excitement, like when a Prothonotary Warbler perches excellent light right in front of you (hey, it can happen!), one can sometimes forget to check a particular setting. But it's the repeated discipline of practicing with the equipment that will make your actions in the field become quick, fluid and successful.
Time & Dedication
This is a huge part of successful digiscoping. Without time and dedication, you're very likely to struggle the few times you're in an opportunity to photograph a candidate bird. It's in repeated attempts that earns the experience, and with the experience comes the familiarity of the process. Once you've "felt" the pattern of success enough times, you begin to recognize it in the field and can settle into that grove. You'll get to the level that you'll sense a successful digiscoping session even before it happens.
Patience & Persistence
Related to time and dedication, but included here I would cite recognizing things that went wrong. Why was there a failure to capture a good image? Reviewing your work and trying to correlate it to the overall progress of your technique is important. What can you improve upon? Are you actually prepared to repeat these exercises to the point that is required to be successful? You have to concede you will have hundreds of missed opportunities. Learn to accept the ones that get away and always recognize through inspiration of the work of others of what is possible to achieve. You can do it too, it's just a matter of persistence. A little discouragement after a failed session can sometimes serve to inspire your next outing. Try not to confuse this type of "failure" with true motivation.
Location Assessment & Appreciation
Quite simply, some places are good for photography and some aren't. You know where to find birds, but just because there are birds there doesn't mean it's a good spot to take pictures of them. UW Picnic Point is often the scene of very interesting reports and warbler fallouts. But how many pictures have you ever seen of mine that were taken there? None. It's too busy. There are too many walkers, hikers, dogs, bicyclists, etc. The mood isn't right, birds are often perched higher in trees and the lighting is generally poor. However, a location like Nine Springs with dikes surrounding settling ponds offers the photographer complete 360 degree access around great water habitat. Location is extremely important. I think many people fail at this particular field skill -- recognizing where it works, and where it won't. Of course, the really great photographers can often take away something creative even in the most challenging locations!
Choose your battles wisely!
Eastern Meadowlark image © 2005 Michael Allen McDowell