visualise yourself sending deep roots down into the centre of the earth. Send them from your base chakra. Then spread them out wide. Feel connected to the earth. Imagine your roots attatching to the earth, then bring them up and imagine them filling your body with the goodness of mother earth. I also protect myself by imaging a space suit around me, although you can choose whatever feels right for you. I also pray for protection. I do this as often as I remember, and ALWAYS before any sort of psychic work.
Before someone told me about grounding, I was finding it difficlt to come out of meditation, and felt uneasy. It really works!