To put it generally - “French kiss” presupposes the direct contact of tongues. The best start is to kiss her on the lips opening your mouth a little.If your girlfriend “responds” to you - try to use your tongue. Don’t “overtry” -you’re not going to smother you girlfriend, are you? Lick her tongue, touch her teeth with the tip of your tongue, sometimes such simple touch works miracles. Play with your girlfriend’s tongue, “clicking”, biting or sucking it slightly. You can kiss in a French-like manner without touching partner’s lips. Come up to each other very close so that the tips of your tongues meet. Try to control your salivation when kissing a girl not to make her feel unpleasant. You should prevent your saliva from getting into your partner’s mouth.