Now, to the meat of a ritual: prayers, spells, giving thanks, that sort of thing.
My terminology may differ from some, but to me, prayer is a petition to the Lord/Lady--usually for help with something, such as love, money, or health. I think of a spell as something which the person involved does, such as making a charm, or reciting a spell--a set of actions.
Once you have invoked, or called, the Goddess and the God, then you can move on into whatever it was that you began the ritual for. A healing? Ask the Goddess and God to heal the person(s) that you are trying to heal. Send them energy by visualizing them well and healthy. Surround them in your mind's eye with healing light.
If it's a protection ritual, call upon a protective Goddess and God and ask Them to protect the person(s) to be protected. Visualize a shield around them, protecting them from all harm. Use herbs, chants, anything you please.
I would like to stress that it is good to do rituals for yourself, too. In fact, that is probably who you will do the largest part of your rituals for over your lifetime.
If all you want to do is cast a spell, and don't want the ritual involved, you can use my short Quarter call while visualizing a bubble of energy around you: "Quarters Four, I call thee round, between the worlds we are now bound." Then proceed to the spell.
I include more information on spellcasting later; for now, I'm dealing with ritual. But to cast a spell is to raise energy, program it, and either release it or take it into yourself. Empowering something to drink and then drinking it is an example of taking energy into yourself.
For raising energy, you have a number of options--you can sing, or dance, or play an instrument, or meditate and concentrate upon calling energy to you. Be creative. I find chants work very well.
To program it, consider the way you are raising energy first--are you singing? Use a song that reflects your goal. Make one up, if you want to. Are you chanting? Same thing. Are you meditating? Concentrate on your goal. Visualize your goal coming true. Don't use the "And I wish I had a pony" mindset. Visualize the actions you need to take to achieve your goal, if you can. If it's something out of your control, simply visualize the end result.
Sewing, molding something in clay, and making an herbal mix are all appropriate actions for this point in a ritual. You might make a talisman, a small bag of herbs to carry with you, a pillow to aid sleep (there are, like, a zillion recipes for those things), a Witch's Bottle (a bottle filled with items for protection that you bury on your property or leave in a window), or create a mix of herbs to bless something with (I've mixed herbs together to bless everything from my threshold to my bed). Knot magic is also handy; for more on that, I suggest you read Scott Cunnningham's book, Earth Power. He devotes more time and space to it than I can.
Giving thanks and praying are, essentially, telling the Lord/Lady a) what you/your loved ones/the world need and b) what you are thankful for. Your own words, in a coversational format, are often enough; if you're more comfortable with a ritualized prayer or giving of thanks, there are plenty of resources that offer them.
When you've complete the activity, it's time to move on and end the ritual.