The easiest way to go is to decide before the session who will be leading and let that person lead for a whole tantric session.
Another exciting way to go is to alternate leading role during the session.
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.