If you are at a restaurant, bring along your favorite breath freshener. Excuse yourself after dinner and go to the bathroom. Freshen your breath and then, to make sure your breath smells good, hold your hand up to your face, breathe, and smell.
If you are brave you could put your arm around her waist when you two are laughing and say something playful like “You’re so cute!” Offer to give her a piggyback ride, or tickle her a little if she likes it. Don’t do this constantly, and when you do it, do it respectfully. Don’t grab her breasts or butt. Flirting will make her more open to kissing you. Think of kissing as reaching the top of a mountain. You have to hike a little to get to the top.
The kiss should stay private too. Don’t kiss and tell. This is rude.
You can say something like: “I really want to kiss you right now. Is that okay?” or “Do you want me to kiss you now?”