My first few times I went to the EF Mass, I sat near the back of the congregation. When they stood, I did the same, same for kneeling and sitting parts. Iāve been to a variety of churches in 2 different dioceses for the EF Mass, and some of them, the congregation does more of the serverās responses compared to others where they do very few of them. No one gave me a hard time at all for being new to that form, in fact I emailed a priest before my first EF Mass and he only says that form of the Mass - he was very helpful in his email response with a few hints like sit near the back, dress nice yet conservatively, and do as the other faithful do among a few things.
Its best to use the red missalette a few times as it does show some of the postures and explains things a bit. If you plan to go more often and you are confident enough to use it, then invest in a good Daily/Sunday Missal by a publisher such as Baronius Press or Angelus as examples.