start from the root and work your way up. do not focus on just one chakra, the energy will pool, cause an imbalance in the flow of energy in your body, and make you sick. an over active third eye can cause migraines among other things. also, just because you have an active third eye doesn't mean you'll see spirits, some people just can't, you might need to do some other exercises, or the energy flow could be stopping you.
i recommend you use the link above to help you. if you have balanced your other chakra's, there's crystals such as amethyst, teas you could drink, or incense you could burn to help you.