A general ritual that follows no particular tradition but borrows from many.

The alter can be decorated with symbols of change. These signify the midpoint between Winter and Summer, i.e. the Spring, when the old is being put out and the new welcomed in. Look around you in nature for such symbols, e.g. plants and flowers that are sprouting up such as the snowflake. A cauldron with a fire set to be lit can be made ready prior to ritual or use some candles instead. Candles can be orange (representing the fire, the coming heat of the summer), or white (new beginnings). You could also use brown as symbolic of the pregnant earth giving birth to new life. If snow is on the ground, melt it and use for water during the ritual or casting the circle.  

After casting the circle, pause for a while noting the dull light and darkness in the circle. Be aware that Imbolc is a fire ritual, one that represents the coming light of the God when life on earth is renewed through the Goddess.

Say the words;

    The darkness swells, her belly nurtures
    The light of life, I sense thee brighter.

Light a (orange or brown) candle and incense. The lighting of one candle symbolises that the God is awake, his light is distant but he is coming.

 The Lord and the Lady, God and Goddess,
    From the womb of the earth, the God; Success!
    He bringeth full light, a warming caress,
    The Lord and the Lady, as One, we address!

A symbolic act of lighting the remainder of the candles or cauldron is now undertaken. This symbolises the growing rays of the sun, the growing power of the God that the Goddess has brought forth once again. While this ritual uses candles or a cauldron fire to symbolise the act, feel free to substitute your own if you so wish. The symbolism should represent the old going out and the new coming in. When lighting candles or the fire, say;

 The light of life, the sun in the sky,
    Reborn, Renewed, by the Goddess, we delight!

You may if you wish walk around the circle holding the light before you. Alternatively, place the light in the East to symbolise the rising sun (or if North is your direction of power, place it there).

Now is good time for any acts of clairvoyance or for looking into the past and future.