Franz Bardon is the only author I know of who expounds simply yet profoundly upon the elements. I'll give you a rough draft.
While we say there are four elements, there is actually only two; the active (masculine) and passive (feminine), known as the electric and magnetic fluids. Their symbol is the sun and the moon. The elements are their extension. Fire, due to it's light, heat and expansion, is predominantly electric, and Water, due to it's darkness, coldness and contraction is predominantly magnetic. Air, which is active, is the equilibrating element of these two forces and has the qualities of both, being "wet and dry". Earth, which is passive, is the solidification of their interplay and is therefore electromagnetic. Each element has two poles - a plus and a minus, having good and bad effects.
The elements have twelve emenations; four in each plane of the physical, astral and mental realms of excistence. On the mental plane, fire corresponds to the will, air to intellect, water to feelings and earth to consciousness. On the astral, they correspond to the four humours of the soul, with fire to the choleric temper, air to the sanguine, water to the melancholic and earth to the phleghmatic. On the physical plane, fire corresponds to the head, air to the lungs, water to the abdomen and earth to the flesh and bones.
All the elements springs from Ether, which is God Himself. I can see that you're a Christian, so i'll try to elucidate a few matters before moving on to the symbolism.
We read in Genesis:
"In the beginning God created the heaven and the earth." -- heaven is corresponding to fire, the first and purest of the elements, while earth corresponds to the last and grossest of the elements.
"And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters." -- earth being void is a metaphor for the unmanifest state, the abscence of the elements. Darkness is an aspect of the water element, but properly speaking, it is not refering to the element of water, but the undifferentiated state of God, both male and female and yet none of them, containing all things in potentiality. The primordial waters are also present in the creation myths of the Egyptians, the Greeks and the Hindus.
"And God said, Let there be light: and there was light. And God saw the light, that it was good: and God divided the light from the darkness. And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day." -- fire is the first element, the principle of creation. It is in contrast to darkness, and in fact, is co-dependent with it, because light cannot be without darkness; they define each other. And thus came the differentiated state of excistence to be.
"And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters." -- water here has a two-fold symbolism; for one, it represents the primordial state of undifferentiation, and second, it represents the differentiated state of creation. The firmament, as we are told later, is heaven, the fire -- fire is the creative principle and water is the created. Consider the terms "God the Father" and "Mother Nature."
The Indians use geometric figures to meditate upon. Ether is symbolized as a black or indigo egg. In consideration of the above, we see that it is a symbol of Gods potentiality in his unmanifest state.
Fire is a red triangle pointing upwards. The three corners symbolize the number three, being the number of manifestation, of which fire is the initiative principle. It points upwards to it's source above.
Water is a silvery crescent moon, symbolizing the inherent duality of the created principle.
Air is a blue circle, symbolizing it's neutral disposition.
Earth is a yellow square, symbolizing the completion of the work.
In this connection, Pythagorean philosophy of associating numbers with geomatric shapes is interresting. The circle we might consider Ether, symbolizing the undifferentiation and eternity of God. The Monad, that is, number one, is symbolized by the dot in the circle. We might consider this fire, as the first manifestation. The Duad is symbolized by the line within the circle, symbolizing the duality of creation with its two poles. This we might consider water. The Triad is a triangle, symbolizing manifestation -- the triad is composed of both the monad and the duad, like air partaking of both fire and water. The Tetrad is a square. The Pythagoreans considered the number four as the "greatest miracle."
On our physical plane, the elements don't excist in their pure form - they are all earth, because everything corporeal has been made by the the mixture of the elements. Consider the positive and negative composition of an atom. Physical fire is dominated by the element of fire, and this allows for a certain analogy, but confusing the two would be like to mistake the body for the soul.
Personally, I find the elemental association with the attributes of my character to be an effective way to understand the elements.