The title to this little article is a question that people sometimes ask.  The answer will vary depending on the subject and the situation. You dont want to appear to be a predator, so dont try and sneak directly toward say a stationary bird or anything for that matter.  If trying to approach a subject a zig-zag approach with pauses is far better.

If shorebirds obviously can see me on say a tidal flat, I pick up a little bit of stick ( so my hands dont get sandy to touch my camera gear ) and stop and dig in the sand as I close the distance to the bird. I deliberatly flick sand and water about with the stick so I look like anything but a predator. I look like I'm interested in anything but birds. I've used this technique with a lot of sucess, you can often see the intended subject immeadiately relax and go back to its feeding or preening. With Red-rumped Parrots I modified the technique by pulling our bits of grass and tossong them about. While using these techniques i'm keeping low and squatting.  Often birds will come towards you. There is a limit to how close some birds will allow you to approach, so be observant for signs of nervousness and stop your approach. I know of many bird photographers who slide along on their stomachs in a sort of commando crawl on the tidal flats, often with a bit of cammo fabric on them. This certainly works, but my back ( and motivation ) is not up to it. So play to your individual strengths.

              A Striated Heron hunting small fish.  I approached this bird using my little digging stick technique.

A technique that is easy, is to sit still with a log, rock or something breaking up your outline in a place where wildlife want to come to, ie where they drink or to a food tree. I think most animals are colour blind, but dont wear your brightest or most contrasty colours if you want to be inconspicuous. I have also made a simple cloth hide that goes over me and my gear which I use sometimes.

A really good way to get close to birds is to establish a bird bath of some type. Make sure it is up high enough to discourage cats. I have maintained a bird bath in bush near my home for some years and it has provided lots of good photo opportunities as well as providing safe water for birds.

                                                                Eastern Rosella photographed on birdbath I maintain in bushland  near home.

Some small animals will freeze motionless as a defence. If say a reptile or amphibian chooses to do this, if you make a smooth approach and don't shake or break anything near them you can get very close.

Insect life can be approached fairly easily by using an alarm clock, ie early morning, particularly after dew or rain they can be photographed while still cool and 'sleeping'. Insects are also more photogenic when covered in dew drops. If the sun is up try not to let your shadow come on your subject, often a sure way to scare wary insects.

  Common Grass Blue butterfly, perched on Plantago. Photographed early morning near home.

So there isn't one answer on how to get close, become an observer and think about the situation.  Long lenses are good but there is no substitute for closing the distance as much as possible. This will lessen the effect of camera shake and atmospherics to help you get the highest quality photos possible.