The most important "bird-stalking tricks" are obvious: No bright clothing, no loud sounds, no quick moves, avoid open areas... However, a few others deserve special consideration.
Sitting quietly in a good place doesn't sound like much of a strategy, but it's a surprisingly good one. If you find a spot with things that birds like -- food, water, shelter -- just find yourself a comfortable, out-of-sight place to sit, keep quiet, and don't move a muscle. Soon you'll discover that, at least to birds, being still is almost like being invisible.
Bird scientists, or ornithologists, have found that while some birds seem able to conceive numbers up to about seven, most birds can count to approximately "one." Therefore, if you have a bird feeder, you might consider placing next to it a large cardboard box or some other shelter big enough to hold you. Once birds have become accustomed to the box and are visiting the feeder again, have a friend accompany you there. You enter the box, but have your friend go away, and now you wait for the birds to come. The birds have seen "one" thing approach the feeders, and then "one" thing walk away. When birds begin returning to the feeder, if you keep quiet, you'll have quite a view!
"Spishing" is the production of a special shhhh-shhhh- shhhh sound, or a similar squeak or hiss, in order to cause a bird to show itself. For example, maybe you know that a bird such as the White-crowned Sparrow at the right is in a thicket or behind a shrub, so you steal near, spish, and up pops the bird to look around and see what's going on. Spishing doesn't work with all birds but with some it's almost magical.
Later you'll learn more such tricks on your own. As you learn "bird psychology," you'll find yourself able to guess how to outsmart birds, and you'll find that your skill in putting these insights into practice can be honed to the point where, really, stalking becomes an art.