Sage is the most known herb to smudge with. This is because it has many positive effects. For example, it cleanses the air in the house, which also removes the negative energies. It helps relax and improves sleep. It takes away stress and boosts your mood. Its spiritual effect is to attract good spirits and bring positivity.
WARNING. Always follow safety guidelines when smudging and playing with fire! Never leave the smudge stick alone when lit up, burn it only on a fire safe plate away from flammable materials and draft. Make sure it is fully extinguished when left alone.