Go to Church.
Read the Scripture before the Mass. The readings are here.
Pray for the priest, sermon, and listening to it prayerfully.
Invite the Holy Spirit to speak to you and all those present through the service.
Arrive a few minutes early - please get there early, not just for a good pew place, but for a moment to collect, quiet, and pray for yourself before you pray with everyone else.
Turn off the phone. Do not text, email, surf, or anything with your phone. Only exception: pray apps like Magnificat or Divine Office
Take notes from the homily and mass, if not during than after the service. A note card and pen are your welcome companions for worship time. You will hear words, write down those words.
After the service, discuss with family and friends your takeaway.
If possible, listen to a homily via podcast on the day's readings. Recommendation: Word on Fire Ministry.
Do not compare your priest to your favorite famous priest.
Do not come to church as a critic seeking fault with the litrugy, homily, priest, or congregation. Grace is everywhere, don't close the door.
Respond generously with whatever the Holy Spirit asks of you. Because the Holy Spirit will always move upon you.

Bonus: Pray a Hail Mary and the end of the Mass to accept the Word of God with an unconditional Yes.