Hi
I would say: Start slow, make it a bit funny and see how she reacts.
Don't go in full berserk, if you do that it's most likely that she will chicken out
Give her some light (really light) spanks (<10) on her ass during sex.
Some dirty talk - don't call her a filthy whore in the beginning, a "naughty girl" works much better.
Gently pull her hair (grab it close to her head)
Tie her up a bit, but then don't dominate her. Just play with her and give pleasure. Or tease her and then play some "edge and denial" - but let her cum after that. It's her reward and if she likes it it's more likely that she will do it again
For example:
Master had some issues with race-play in the beginning (I guess many Germans have troubles with it because of their past, but that's not the matter here), so I told him in exaggerated accent "Yeah, mount me my white stallion". We were both bursting in laughter that next few times I told him to "use my asian ass", that his dick is superior, and so on.
Now he has no problem with calling me a "slant-eyes bitch".
Most important: Respect her wishes. If she don't like it - don't force it.
Maybe her submissive side will wake up, maybe not - it's not for everyone.
Please don't do the "If you don't do it, I will break up with you." BDSM is not just dominant sex, it has a lot to do with trust.
So, make small steps.
Kind regards
Ra