My experience with my 6 birds is pretty good. The main thing is if you are going to let them out you have to watch them like a rooster would. If they do something wrong (and they will do it repeatedly) you have to correct it each time. How ever you want to correct the behavior is up to you, but in my case, if they see me coming towards them with a particular corn broom with a blue handle, they know they are somewhere where they should not be. They will immediately get back onto my property even if they have to come towards me while I have the "broom of death." Most times all I have to do now is walk towards the offender in a brisk walk and they will get back on my property. The same goes for the road, (they don't seem to go onto the road, they just eat the weeds at the edge - about 2-3ft from the edge of the asphalt) sometimes a streetbike will scare them back towards the house, but most cars have no effect. I have not had to bring out the broom of death as far as road going behavior is concerned.
One thing I do think is important. If you are going to pick them up from a place where they should not be and they do the mating squat for you (if you have hens), ALWAYS pick them up gently. You do not want them associating rough handling when they squat for you. The reason being is that out of all the ways to wrangle a chicken, the easiest is when they sit still so you can pick them up. After you have them ALWAYS set them back down gently in the place you want them to be.
In short, I think my chickens realize that the broom is the thing to be afraid of. When I walk towards them like I describe they probably think I "might" have the broom and get back on the property. They probably associate my hands and physical touch with food or gentle behavior. Be nice to the fuzzy-butts!
Whitey
(edit):
I guess I should add that I have never hit my birds with a broom. When they were learning, all I had to do was give them a little bump on the rear and they would fly and cackle. Now all I have to do is extend it out with my arm and sweep it towards them and they move away from it (in the direction I want them to go). My statement about them coming towards me even if I have the broom is what has evolved. If they start coming towards me (away from where I don't want them) I do not continue to move towards them with the broom. They seem to have learned well.