Three principles of prayer: 1. Keep it honest. 2. Keep it simple. 3. Keep it up.
It doesn't really matter so much what the words are I don't think - maybe if you're a real expert in prayer you could do it through silence. But I think sometimes it helps to express it and to know you're expressing it to God. Paul talked about praying with your spirit and that's basically what it is, it's expressing what you feel deep down in a language which God gives you.
Prayer for the city is important. For every city in the world, the city should be prayed for. Particularly for London, it is a strategic city for the UK as well as the world, therefore the future of London is significant to the UK, and also the rest of the world.
