Scott- Sex. He wanted both of your first times to he as perfect as he could make it. He made it super romantic with rose petals, and candles and cheesy music. But it was the best it could be, as it has been every time since then.
Stiles- Kiss. Being awkward and clumsy he was nervous about the dist time your lips connected. But once they touched,all his worries flew out the window.
Derek- First Date. He'd never been on a date before, and so it meant a lot to him, to keep you happy. He was nervous you wouldn't enjoy yourself, but it was him, so of course you did. He could of taken you to a sewer and you would still love him.
Jackson- Vanilla sex. He isn't used to the mushy love making, but wanted to let you know how much you really do mean to him. He was nervous about revealing too much or screwing up, but he didn't. You loved it. You love him through everything.
Isaac- Eating you out. He was nervous his wolf instincts would take over, and he might hurt you, especially where teeth were involved. But you both kept as calm as you could, and you guides him through it with your hands in his hair, and an encouragement of sighs, whimpers, and mewls.