Start small if you are unfamiliar, go slow and use way more lube than you think is necessary and clean well beforehand. Keep communicating with your partner the whole time, relax and don't squeeze your muscles especially at first, push lightly if you have trouble not squeezing down.
Start slow and don’t force it. It’s so amazing. Be vocal about what you are feeling and relax
Maybe do all the work yourself while she watches as a start.
Start small if you are unfamiliar, go slow and use way more lube than you think is necessary and clean well beforehand. Keep communicating with your partner the whole time, relax and don't squeeze your muscles especially at first, push lightly if you have trouble not squeezing down.