Which essential oil do I need?

Reach for soft florals and warm woods. Lavender is the usual starting point — familiar, forgiving and easy to blend. Cedarwood and Frankincense sit underneath it and make the whole thing feel less sweet and more grounded. Roman Chamomile is the gentlest of the group.

Three or four drops in a diffuser an hour before bed is plenty. More is not better with florals; a lighter hand reads as more pleasant.

Citrus does the heavy lifting. Lemon and Wild Orange are the two most people know, and both lift a kitchen or a stuffy room quickly. Bergamot is the more interesting choice — citrus, but with a floral edge that stops it smelling like cleaning product.

Citrus oils are volatile, so the aroma arrives fast and fades faster. Pair one with a wood or a herb if you want it to last.

Peppermint is the classic — sharp, cool and unmistakable. Rosemary is the herbaceous alternative if peppermint feels too strong. Both are commonly diffused at a desk in the morning.

Start with two drops. Peppermint in particular is easy to overdo in a small room.

Blends earn their place here because they are already balanced for you. On Guard is the spiced, autumnal one. Purify is the sharper, cleaner-smelling option. Air is the one people reach for when a room feels stuffy.

These also come as sprays, washes and cleaning concentrates if you would rather not measure drops.

Roll-ons. The oil is already diluted in a carrier at a sensible ratio, the bottle does not leak in a bag, and there is nothing to measure. They are also the simplest way to try a blend before committing to a full bottle.

Three bottles cover most of what people actually want: Lavender for the evening, Lemon for freshening a room, and Peppermint for a lift in the morning. Add a bottle of fractionated coconut oil so you can dilute for skin, and a diffuser.

Starter kits work out cheaper than buying the same oils individually and take the guesswork out of choosing.