A simple way to choose what to do in a tantric session is to decide who will be leading the session before you start.
Why is it important?
Because you and your partner might have different ideas and fantasies about what you want to share.
To avoid conflict, discussions or having to make choices, simply choose who is the leader for that session.
Accept the fact that you can experiment of course. It is ok to take some small risks and expand your sexual horizon.
Keep an eye on your partner.
Ask questions like "Does this feel good?", "Do you prefer this or that?", etc.
Don't engage though in a rational discussion while in the tantric sex session as this totally kills the excitement and the tantric flow. Keep that for the feed back minute after your session or in the following hours or days afterwards.
If you are leading, trust yourself and make choices, take decisions! This will give rhythm to your tantric play.
You can lead, verbally or with body language, guiding your partner with your hands.
If you are asked to do something you REALLY don't want to do, let your partner know that this goes one step too far for you.
It's very healthy to have this "veto" right so that you feel totally secure in a tantric session.
As a general guideline, I would encourage you to use your veto right only in very rare, extreme cases.
Very often, a new tantric idea might stretch a bit your comfort zone. However, dare to experiment.
As soon as you try, you will notice that you might actually like it a lot.
If your partner is leading, really let go of trying to direct.
PLAY THE GAME!
ACCEPT THAT YOUR PARTNER IS IN CHARGE FOR THIS SESSION!
If they suggest a practice, of course don't be there passive asking them to do everything.
Engage! Play! But let them lead!
This is one of the core keys to successful tantric sessions.
It is this ability to lead and be led.
You can alternate the leading role in a session or between sessions.
For instance you can lead for 10 min and then let your partner lead for another 10 min.
Or you can bring in an idea, practice it and let your partner bring in the next idea.
If one of you is way more inspired, has many wishes and the other is comfortable with being led, one partner can keep the leadership role for a few sessions or even all the time IF IT'S SOMETHING YOU BOTH want.
I would say that in most situations, alternating the leadership role is more balanced and gives space and power to each one of you.
Remember that these "technicalities" are something you discuss together before or after a tantric sex session.