First of all it would use ancient language and worship forms, because the nature of religious language has always sought legitimacy and authority and to do its work by an appeal into the past. Plus, we moderns have a dearth of religious forms in the present.
However, there is still a duty to reform liturgies to bring them from the feudal past into the industrial and post-industrial ages, and furthermore at least to reflect something of democracy and liberty. We should not be frightened to move away from King and Lord language, for example, but also move festivals from the simply agricultural based.
Whilst creeds and articles are part of the inheritance of the Church as a whole, I'd keep them in their glass covered cases. Then, while some liturgies were clearly more traditional and proclamational, with uses of "according to scripture" etc., others would take more account of contemporary theology and movements.
For example, whilst one liturgy might contain:
Christ has died,
Christ is risen,
Christ will come again.
Another might shift the focus and state:
We, the baptised people, died and rose
And move towards fulfilment.
I note how many people in intercessory prayers now say, "We remember.." and "We think about...", and therefore it seems to me that much liturgy should be consistent with this ordinary way of thinking. In other words, theological language should be given a clear religious humanist twist, this on top of its democratic and liberal turn.
At the same time (for we postmoderns) we don't forget the place of the story and poetry in the spiritual life. Liturgy is not an exercise in history, social science or science, however much these may be incorporated, but in the dramatic movement.
Intercession remains in that it brings forward real concerns and real names as a focus for faith and for the world. We should always remember that liturgy and ritual are for a purpose of renewal and binding, and this should be the principal focii. It is like a cleansing, going in, doing the main event, and coming out to go out into the wider world. Ritual with tokens is a gift-exchange above and beyond but into all other exchanges - those exchanges involving from members a keen sense of social and ethical purpose.
Before that central ritual can come several supporting readings and a talk. Music and the arts generally are important for spiritual uplift, with different emphases on quality and accessibility. The central ritual can be made spare to emphasise its special nature, and so there are shorter services of liturgy containing readings, talk, prayers and at times musical involvement too.
The Bible is presently over-emphasised, and really Paul is given far too much place. So I would have readings from several sources. There ought to be far more emphasis too on the Jewishness of Jesus, and his and his family's thought forms ought to be reflected better. The Greek side, so to speak, can look after itself.
There is an important place for other religious and philosophical insights. What God means can be enlarged, and made multiple. So can the idea of the Holy Spirit as a creative motivator. The trinitarian terms are still available, but they can loosen up consistent with but not limited to the first ways these terms were understood (though I concede the difficulty of grasping ancient thought-forms).
I would have bishops and priests, with all the councils, as a partly rational and diverse way of organising the Church with checks and balances. They are facilitators for building up worshipping and serving communities. However, I would scrap the promises beyond a general commitment to faithfulness and towards developing a spiritual life and seeking self-honesty. There might be a general commitment to the ways, means and decisions of the Church, according to conscience.
I would emphasise individual conscience as the principal doctrinal position for bishops, priests and lay people. In other words, I would make explicit the fact that we as individuals rightly decide what we believe. Thus ministers, lay and ordained, would preach with knowledge and responsibility to who is in the congregation, engaging in dialogue with others, probably but not necessarily drawing on the readings. Sermons ought to have moments of talk-back at the end for quick responses, with suggestions for further discussion.
The main rituals of the Church would be open to all. In other words, the sharing of bread and wine would be without entry conditions. The meaning of the sharing of bread and wine would be open to interpretation, from a feast of nature to the real presence of Christ.
Prayer also would be explicitly understood individually, from a form of contemplation, to meditation, to addressing a hearing God.
Some churches would be no more than homes or rented places, others would be owned and decorated and inherited and historic. Some would be simple and some elaborate.
It is interesting how when you visit church members in houses how many have images of Buddha and Krishna as well as Christ. That ought to be so in churches as well. They are all objects of reflection and devotion. Candles and colours are obvious aids, and something of a yearly spiritual timetable can be maintained.
I would emphasise religious education and discussion for members, that people who want to be involved further could go into groups for discussions and further spiritual practice. Children would learn about their own faith and, as they got older, comparisons with other faiths, as well as thinking about how to apply their personal faith to community involvement.
So now this is set up we can get everyone ministering and deciding, and off we go.