Many people who practice witchcraft like to use elemental magic spells, as it is a very natural form of magic. It's also much easier to learn (and remember) the basic qualities and attributes of 4 elements rather than learn hundreds of other correspondences for herbs, stones or oils. Though it may be simpler than some other spells, elemental magic spells can still be powerful.
First off, we have the element of air. The qualities that air represents include: ideas, inspiration, creativity, intelligence, travel, freedom, new beginnings and mental clarity. If you want a spell for any of these ideas, you should incorporate air into your magick. Items like feathers, bells, incense and quartz all have air attributes.
Next is earth. This is an element that stands for grounding, all forms of nature, money and prosperity, growth, rules and responsibility. If you want to represent earth on your altar, you can use a pentacle, stones, or a bowl of earth or rock salt. earth spells, crystals and herbs are often used since they are natural items directly from the earth.
Next up for elemental magic spells is fire. Candle spells are the most popular kind of witchcraft spell, and are a good example of using fire. Fire should be used for spells involving passion, energy, strength, creativity and anger. Items for fire include candles (obviously) as well as volcanic glass, and the athame (though some traditions have the athame associated with air). Fire spells usually involve candles, but not always.
And lastly we come to water. Water energies are often used in spells for love, fertility, friendship, healing and sleep. But spells don't often call for actual water. Crystals like aquamarine and moonstone make great "water" additions, as do herbs like lilac. A chalice is the usual altar tool to represent the element of water. If you do use water in your water spells, try to use naturally collected rainwater.