We know that Jesus asked for the little ones to be allowed to come to him, and that we should all be as children.
Children have a vast capacity for understanding, so we should not hesitate to enable them to begin their understanding of the love of God from the beginning of their life.
When you enter the church, you can assist your child to sign themselves with Holy Water; this is a reminder of Baptism and they can reflect that this can be ..."the wetter the better"! Your infant can be signed by you or by siblings.
So that your child or children can see the priest, do sit as near to the front as you can, or at the end of a pew so they and you can lean out to see what is happening.
When your child can walk they will also be able to genuflect.
When you make the sign of the cross, do encourage your child to copy you; it helps if you're signing yourself slowly, deliberately and with wide movements.
At the beginning of the Gospel, we make a triple sign of the cross, that God's word be in our minds, on our lips and in our hearts. Alternatively, you can help them see it as "May I think like Jesus, speak like Jesus and love like Jesus".
During the Liturgy of the Eucharist, at the consecration, you can hold your baby or young child and face them towards the host and whisper to them "Jesus loves you, He is here".
For pre-school children, you may wish to cuddle your child on your lap during the consecration and at the elevation to point and whisper, "Look, Jesus is here, he loves us all".
For older children, use a children's missal to help explain what is happening and support your child to follow along with the Mass.
It is good to explain what the servers are doing and why the items are in the church (altar, tabernacle, candles, chairs etc). There may be wonderful statues or windows and you can quietly point them out; this is because they have a reflective value rather than just being decorative.
Teaching your child the Lord's Prayer as early as possible is great; to say this prayer together while holding your child emphasises the theology.
At communion time, before their First Communion, help your child to fold their arms across their chest and to receive their blessing reverently.