Elemental magic
These forces balance the planet on which we live and make life possible. The elements are unavoidable under every system of magic I know of, as well as an essential part of the symbolism present in western astrology and tarot. Common symbols like the pentacle and the Native American medicine wheel also represent this balance. There are witches who specialize in working with each element, all with rich traditions. Each of these components can be its own category of magic study.
For those called to work with the elements, there are many ways to connect with that power. You can analyze your own astrological placements to see the balance of elements. You can utilize them in ritual to aid your goals. Below is a list of the common correspondences and symbols associated with each of the elements.

Fire
Energy and spiritual life, heat of the day, anger, passion, that which cannot be put into words; tarot suit of wands
Direction: South
Colors: White & red
Symbols: Sun, lightning, volcanoes, rainbows, salamander,
Can be represented by: Candle, lamp, athame (dagger), censer, burning herbs, petitions written on paper
Water
Emotion and imaginative life, healing, purifying, cleansing, growth, love, dreams; tarot suit of cups
Direction: West
Colors: Blue & silver
Symbols: Wells, rain, rivers, mist, fog, the ocean, fish, seashells
Can be represented by: cauldron, mirror, chalice
Air
Intellectual and cognitive life, thought, mental processes, communication, connection, relation; tarot suit of swords
Direction: East
Colors: Yellow & orange
Symbols: Wind, clouds, trees, butterflies, herbs, birds,
Can be represented by: Bells, incense, feathers, wand, incense, visualization
Earth
Behavior and material life, rest, growth, abundance, security, groundedness, work, wealth; tarot suit of pentacles
Direction: North
Colors: Black, brown, & green
Symbols: Mountains, stones, soil, rocks, fields, toads, bull, grapes
Can be represented by: Stones/crystals, pentagram, bowl of salt, photos