CoD in a nutshell

Talk openly about your fetishes, take your time for the clit, provide the right mixture of rough and soft. Dominate her. Cuddle afterwards, tell her what a beautiful person she is (appearance and personality)
I'm open for detailed questions

But if you want to try something new like i dont know a threesome how would you tell your partner

This I can't answer, because I'm comfortable enough to talk with my partner about literally anything.

Fine how about bdsm

Uhm same. Just tell him/her. There's nothing to be afraid of. They won't make fun of you. Worst case scenario is a 'no'.

Whats the best way to take it in the ass?

Start slow and with lots of lubrication. I reckon missionary the best to start, when you're used to it, go after personal taste.