Juniper has been used as an incense in Tibet and in herbal remedies - it is a good purification oil and can help clear the mind - it clears your energy field and the room you meditate in too, thus enabling a good link with your higher self. Experiment with the oils and don't use one oil for too long try blending some. The woody oils are great, for they ground you as well as reaching up to the heights, try pine, cypress, fir, spruce, sandalwood, amarys, ho-wood - rose wood (provided it is obtained from sustainable sources).
Luv
Binah