Start by connecting with the earth. Grounding your energy, cleaning, and barefoot walks [if there's snow in your area skip this one for now] are some common ways to connect. You could also work on opening your root chakra which would ground you.
I don't know many spells which would qualify as 'earth spells' but burying objects can add the earths energies to them. Stones and herbs are earthy too [though they too have energies polarized with different elements] look into spells using those objects.