The earth has it’s own magnetic energy and vibration which interacts and harmonizes with our own. There are some simple ways to connect and “ground.”
Being outdoors and connecting with nature is one of the easiest, but not always the most accessible. Walking barefoot is also a great way to ground with earth energy.
Mediation is another powerful way to center yourself and connect with the earth energy. Breathing is also a very strong and quick way to bring your awareness to your body and your physical plane of existence. Physical exercise increases this sense of grounding and being in your body as well.
Crystals are very helpful at helping you ground because of their unique energetic impact on us. Minerals are the oldest known life form and have a very subtle but powerful way to impact our body, mind, and spirit. Using them on your third eye or using a crystal grid around you to meditate can dramatically increase your intuitive abilities. I think they work very strongly when placed on the third eye after doing intense spiritual work.
If you need to ground quickly to center, hold something cold, focus on your breathing, and let any feelings you have move through you and flow.
Having plants and elements from the earth in your home is another way to center to your energy.