non-verbal communication.

These are the signals that you "send" to other person.If you know these techniques it could have great effect especially on your first date and in the beginning of your relationship.This is important part of your relationship with your partner.

There are two main things.
First is your body language.
Second is that you have to learn your partner's body language.If you can "read" these signals you will get to know him/her more deeply.This will help you to see when he/she is ready for first sex or you will show that
you are ready for that(for example).

How to play this game?
The main rule for you here is to be self-confident and relaxed.

Elements:

Eye contact-look him/her in the eyes while speaking.In that way you show that you are interested in what he/she says.

Smile - don't smile constantly but regularly.Let say that your partner make a "stupid" joke - smile, imitate that you like it.

Posture - it is also very important.

Personal Space - you must not be too close to your partner, especially in the beginning of your relationship.

There is one other trick trick.You can start to imitate someone.This could be his/her favorite actor for example.