I never used to put Cheucie's collar on very tight so that she could get out of it if need be, say, if she caught it on a branch. If it came off, she would bring her collar home in her mouth, set it down, sit, and look at me, indicating that she wanted it put on "now". The trick was this... For her first collar, I got a bright red one and made a big fuss about it as if it was a special present, from presenting her with the box containing it to excitedly opening the box. Then, when I put the collar on her, I admired and praised the look of it whilst petting her. I even put her in front of the mirror and showed her how nice it looked. After she got use to it, the flea collar was easy. Funny thing though - she would come home sometimes still wearing the red collar but no flea collar.