If you want perfume oil for your body, make sure you are buying a finished personal fragrance intended for skin.
Then application is easy.
Lily Essences uses a roller so the fragrance can be applied directly to your skin without needing to pour anything onto your fingers.
Pulse areas such as the neck are particularly useful. Wrists work too, but repeated handwashing can naturally shorten how long fragrance remains noticeable there.
For your first use, start with one light pass.
After that, the amount is personal preference.