A couple of tips for people who want to try to catch a stray or loose dog:
* Do not move towards the dog; in most cases, that will just cause them to move away from you.
* Turn sideways. In the doggie world, moving straight towards someone is an aggressive movement. A happy dog approaching another dog in a friendly manner will most often walk in an arc, not a straight line. Turning sideways shows the dog you are friendly.
* Bend over slightly. Dogs "bow" to each other when they want to play. If you bend at the waist or crouch down a little, this can approximate the doggie play bow.
* Move backwards. Again, moving forward is agressive. Moving backwards is more enticing: hey, come play with me! Clapping your hands or patting your thigh can also be enticing in a friendly way.
Once you have the dog's attention, try asking them for a common stationary command, like a Sit or a Down. If the dog complies, praise them in a high, sing-songy voice (yes, men need to use your falsettos for this) while you *slowly* approach the dog in a somewhat indirect manner. Reach for their shoulder, not their head, when trying to get at the collar.
Hope this helps... it won't work every time or with every dog, but at least it should improve your chances and be less stressful for the dog.