I have a couple ideas that come from dog & cat training.
When my cat does something wrong, I say. "Bad, bad girl", in a strong voice and tap/touch her on the bridge of the nose. It doesn't hurt her, gets her attention, and makes her know I mean business. I'll sometimes also ignore her for a while, after I scold her. She's very needy & clingy, so she doesn't like this at all. Sometimes I'll even say, "no, I'm mad at you, you were a bad girl." Whether she totally understands everything I'm saying, I don't know. She is very smart and she knows sit, stay, come, off, down, no, & a few other things.
As for dogs, I had to help my parents train their pitbull to bark, "speak", to go out. We think his old owners might have lived in an apt., so he was probably taught to stay quiet. I just used possitive reenforcement and love to train him. He'd speak when I said to and I'd tell him over & over that he was a good boy, and give him hugs, kisses, and lots of petting....totally gushing over him. He's a needy mush like my cat, so this worked like a charm.
For cats and dogs, I think the best thing you can you is give lots and lots of praise. Pet them, kiss them, even call them a special name (the opposite of using some one's full name when they're in trouble
). I do with my cat... it's Zeal or a nick name usually, but when she's bad it's LADY ZEAL in the "Mom's not happy" voice. I have almost a dozen pet nicknames for my cat and I always joke that it's because I love her so much... if I didn't I'd just call her "cat".
Good luck.