Hello Elisabet! I don't think I have welcomed you to CC before, so..welcome to CC!
About kissing. I would personally avoid french kisses because french kissing just feels too intimate for me, intimacy then leads to sexual activities. You know, the thoughts that you get while kissing like that. Been there. And the Bible tells us that sexual activity outside of marriage is a sin.
Now if I wanted to show affection, then I would prefer a cheek kiss, or a quick peck on the lips. They won't really bring up any intimate thoughts and would be purely for affection. But you need to think about the person your gonna kiss as well, what if a quick peck would bring up the wrong thoughts for them? Then that turns us into someone who stumbled them, that's wrong again. So you need to be careful about this. Before you kiss, ask yourself, why are you doing it? Is it right for the other person too? Would this bring glory to God? Those will help you out.