Let us remember: gathering together in the House of the Lord to worship Him and join together in prayer is such a privilege and joy that we must not fear to draw near to the Lord with our hearts, with our minds, and also with our bodies. The two normal postures for worship according to the Scriptures and in the practice of the Orthodox Church are standing and prostrating. With Great Lent fast approaching, we will have many opportunities for the latter soon enough (more about that next week!). As the faithful children of God, therefore, we must never shy away from taking a position in the Nave that is closest to the altar of our Heavenly Father. The tendency is to remain toward the back. Therefore, be bold! Come and stand as far forward in the nave as far as you dare. Regardless, no one should stand immediately in front of the doors at the back of the church (between the vestibule and the nave).
Normally, when the Royal Doors to the Altar are open, one should stand up, facing the Altar, hands at your sides, or held one over the other at the waist. Do not stand (or sit) with hands in pockets; do not fold arms behind you or across your chest. If you need to sit down, do not cross your legs. Remember, sitting in the church (while encouraged for those who need to) is not the normative posture for prayer. If you need to sit, keep your feet flat on the floor, ready to stand at attention (which, after all, is precisely what "Let us attend!" means). Benches or chairs are provided for our guests and those who for whatever reason need to sit. Please reserve them for this purpose! (To be more direct: children and others who need to sit, eg, during the sermon, should sit on the floor and reserve the benches for our guests and other adults who need to sit. Also, keep the benches clear of purses, bags, and other items). It is always appropriate (even if for whatever reason one might need to sit) to stand during the reading of the Gospel, at the Little and Great Entrances, the singing of the Creed, at the Anaphora (the prayer beginning, ‘Let us stand aright, let us stand with fear…’), the Lord’s Prayer, and during Holy Communion.
[In some Orthodox cultures, crossing one's legs is taboo and considered to be very disrespectful. In North America there are no real taboos concerning crossing one's legs, and we tend to do so to get comfortable when sitting. Should we cross our legs in the church during services? No. Not because it is wrong to ever cross your legs, but because it is too casual, and too relaxed, for being in church. ]
Let me know if you have any particular questions!