Kneeling, the old-fashioned way (Posture 5, below).
1. Standing. This is very popular nowadays (even in parts of the Extraordinary Form Mass), although a pedant might argue that it goes against Matthew 6:5, And when ye pray, you shall not be as the hypocrites, that love to stand and pray in the synagogues and corners of the streets, that they may be seen by men. Moreover, it means that anyone behind you who is kneeling cannot see what is going on.
The 5 sacred postures.
This aside, there are four postures which make use of the pews/seats:
2. Sitting, and leaning back. This is roughly as antisocial as tilting your seat back on an aeroplane. It limits the possible postures adopted by the person behind you - of the ones listed below, your neighbour can still manage 3, but 4 and 5 will be prevented.
Ladies, no slouching, please!
3. Sitting, and leaning forward. Bad for the back muscles, but perhaps the best if you refuse to kneel.
4. Sit/kneeling, with backside on seat and knees on the hassock/kneeler/cushion embroidered with a picture of Micky Mouse (whichever your church provides).
The pope is unimpressed by a bishop's praying posture.
5. Kneeling, with backside unsupported, and body leaning against seat in front. This is surely the most recommended for saved persons, if possible. Of course it is also the most tiring.
An alternative praying position, not discussed here.
Well, now we come to today's question of church etiquette.
QUAERITUR: The lady in front of me is a "Position 2" pray-er, and sits right back when she prays. Thus, when I adopted my own favourite Position 5, I got my hands tangled in her hair. She then switched to Position 3 (leaning forward), at the same time tutting loudly. Should I now keep the territory gained, or should I retreat to Position 4 (sit/kneeling)?
FATHER E. writes: Oh, you must keep the territory gained. Perhaps you can somehow make use of an umbrella, firearm, cuddly toy, or whatever else you carry with you, to help you hold your position.
... or whatever else you carry with you...