Fragrance, regardless of the source be it incense, oils or herbs is the best way to induce an altered state. Fragrance has it's own vibration and is able to change the vibrational energy of the environment and the person. Each fragrance has it's own properties and affects us differently. Though you may not feel the energies of fragrance, you will feel the effect.

Oil fragrance can be applied to certain areas of the body or added to the bath before meditation. Either way the oils are the best source of fragrance.
If you don't wish to use the oils in your bath water, you can add a couple of drops in a small bowl of water and place it near you. You should also place some on your body.

If for any reason you don't want to use oils, Incense is the next best.
I have my own favorite incense which causes me to feel a deep mystical spirituality. It gives me the feeling of being in a holy temple.
Burn an incense before your meditation so the air is filled with fragrance before you begin. You will also need to burn one during meditation. The stick incense will burn slower and therefore last longer.

Just as each fragrance is distinct and affects us differently we will all respond to the same fragrance differently. We will all have a unique scent that is our favorite.
In other words we will resonate to one or two that will evoke images, memories, and emotions from deep within.

You can mix and match the oils and create your own ambiance.

All the oils/fragrances listed below increase our vibrational field and expand our consciousness which opens our inner eyes to see that which is hidden.
All of them heal us in some way.

Lavender-This wonderful fragrance will help to stimulate memories and dreams of past lives. If used for this purpose meditate just before going to sleep. It helps to reveal and remove karmic blockages. It will also unveil inner conflicts and help you to grow spiritually.
Place under the nose and on the solar plexus.
Meditate with this fragrance when there is conflict with your loved ones.

Lilac-This fragrance will create a very spiritual atmosphere during meditation. Place on the lower part of the back of your head and between the eyes. By doing so it will induce long ago memories and clairvoyance. It will help you sense the beauty of your soul.

Eucalyptus-Place a drop between the eyes during meditation and it will open your third eye and stimulate inner vision. This fragrance repels negative emotions and energies.

Frankincense-Use this fragrance during meditation to elucidate obsessions.
It will give you inspiration and true understanding of yourself, situations and others. It can also be used to induce visions. Place a drop or two in the heart area and on your forehead

Hyacinth-This fragrance will help reveal the reason for depression. Using it during meditation will help heal those who went through trauma at birth.
Use this fragrance during meditation if you are pregnant. It helps you to communicate love to your unborn child. Place a drop in the navel area and on each temple.

Myrrh-This fragrance heals and cleanses. Myrrh kindles memories of past lives that create emotional blocks in the present. It helps stimulate revelations through your dreams if you meditate before going to sleep. Place a drop or two on your throat.

Orange-
Used in meditation, this fragrance helps release emotional trauma.
It calms highly tense situations and heals deep seated fears. It is to be
placed on the solar plexus to still nervousness, agitation, and excitement.

Sage-
A very powerful fragrance that impacts our spirituality. It stimulates the knowledge that the soul is immortal. It helps us develop spiritually and stimulates deep understanding. It helps us develop the gift of "knowing". Place on the heart and navel areas during meditation.
Place this on your temples when studying any spiritually authoritative book.