I did over the top praise when she pottied on her pad. Not just little clap, but all out dancing, singing, the works. Each time she pottied she'd freeze and wait for me to clap once, then start singing the potty song I made up just for her. She'd fly over full speed and start dancing too...and of course, get her treat. It was like her birthday each time. So, going potty was the highlight of her life because each potty on her pad meant 'party time'.
If she made a mistake, I'd very calmly say, 'Oh my, that's not the potty pad' and gently place her on her pad. She never got in 'trouble' for pottying. I fussed, using a mean voice, at a dog I had years ago for pottying in the wrong place and it only made her think pottying was bad and she found places to hide when she went potty.
It took forever to get her potty trained. Our babies really want to please us and once they figure out what makes us happy they'll do that every time.