The occult often deals with "secret" information which has to do with divination and other kinds of knowledge about controlling aspects of life and reality. This kind of information is often equated with science in that both magic (of which the occult is a part) and science deal with "cause and effect" If I do "x", "y" follows.
Although early social scientists saw an "evolution" from magic to science and religion, later social scientists (starting with perhaps Malinowski rejected such as sequence arguing instead that magic and religion dealt with the area of the "supernatural" while science dealt with the area of the "profane".
The supernatural realm contains in a sense, two areas religion in which the one is inhabited by human like beings (gods, human like spirits) and the other supernatural, non personified forces (often referred to by the Polynesian term "mana" a kind of supernatural power like electricity which has a dangerous element to it. Prohibitions because of mana are referred to by another Polynesian word "mana". Ruth Benedict argued the first are projects of people into the supernatural and the second were projections of forces and objects into the supernatural.
Not all magical practices are "occult" or hidden. "Hanging a horse shoe on a wall or over a door brings good luck if the ends of the horseshoe point upwards" (the "luck" might run out!), is hardly "occult or secret knowledge, but is "magical". On the other hand, reading Tarot cards or dealing with other forms of divination is something which may need to be learned or in some cases people are thought to have been born with that ability,
If you are interested in the many forms of divination, here is a
list of some of the innumerable forms {from Wikipedia)
The idea of the "cause and effect" relationship is the same in both magic and science. If I do "x", or if "x" happens, "y" will follow.
If I sleep with my text book under my pillow I will get a good grade.
Alchemy is one of the transformative processes associated with the occult. Alchemy involves the "secret" techniques in transforming one substance into another especially base metals into gold. This is a property associated also with the "philosopher's stone" to say nothing of the "Holy Grail" and is similar to the change of wine and wafer into the blood and body of Christ. For the Masons it would appear a similar transformation occurs from rough stones into finely cut ashlars, thence into beautiful buildings. The masonic idea is that the symbolism moves the person to develop spiritually, socially and personally.
Secret information may be hidden in several ways:
Some Examples of Writing System and Symbols
Sigals, are images which often represent a person place or thing. Often they are found relative to supernatural beings like demons and often are thought to have the power to compel some action,
This show some Sigals for summoning specific demons
Alphabets themselves may be seen by some as having supernatural power. Norse runic writing is commonly thought by people interested in the occult as having some occult power.
Ciphers and codes are terms often used interchangeably but technically are different. Ciphers involve a system in which one letter is substituted for another. An interesting example is found in the film 2001: A Space Odyssey in which the computer is named "Hal". Substitution the next letter in each of the letter of Hal's name become IBM!
The "runic" writing system (of which there are several variations). The term futhark derives from the names of the first letters in the runic alphabet the way the names of the letters of the Greek alphabet alpha, beta, gamma give us the word "Alpha-bet"
Hermeneutics refers to the analysis of a work of art (originally of a religious literary text, but now common for almost any text or other art forms like film). While it is nice to see HAL -> IBM from a cryptanalyst's point of view, it is meaningless. It could be any three letter word (at its simplest a three letter word made up of three different letters). It is only in the context of "hermeneutically" examining the film that is becomes possible to assert more strongly that the Hal/IBM relationship was probably deliberate.
Hermeneutics is a way of analyzing a text to arrive at a hidden (occult) meaning, often called the "subtext". On the surface, Moby Dick appears to be a story about a whale and a captain who hunts him. The subtext seems to contain some "hidden" meaning which has religious implications. The names Ishmael and Ahab are biblical, the ship leaves on Christmas day, All the harpooners (Queequeg, Daggoo,Tashtego and Fedallah) are pagans; Queequeg "dies" for 3 days and comes back to life etc. etc. etc.
Predictions and other prophesies are often phrased ambiguously so that the statement and its opposite are both true - depending on your interpretation and what you want to hear.
A Roman general is told about his upcoming battle:
Ibis, redibis, numquam morieris
With which verb does the "never" go?
Ibis redibis nunquam per bella peribis (alternatively Ibis redibis nunquam in bello morieris) is a Latin phrase, often used to illustrate the meaning of syntactic ambiguity to students of either Latin or linguistics. Traditionally, it is attributed to the oracles of Dodona. The phrase is thought to have been uttered by a general consulting the oracle about his fate in an upcoming battle. The sentence is crafted in a way that, without punctuation, it can be interpreted in two significantly different ways.
Meanings and translation:
Ibis, redibis, nunquam per bella peribis.
The other possibility is the exact opposite in meaning:
Predictions based on readings makes some sense when one realizes that some predictions from the stars for example work. The Egyptians predicted the flooding of the Nile by the appearance of the the star Sirius, (the brightest star in the sky - except for the sun) in the morning just before sunrise. This makes sense since the stars appearance varies regularly from season to season. It is a short jump (but a misstep) to think if you can predict the flooding of the Nile by the stars you can predict something about a person from knowing in what constellation of the Zodiac then sun was when the person was born.
Similarly for Tarot cards and other forms of divination about an individual, the various cards which have meaning like "wealth", "change" etc. may allow the person to examine the ways in which their current "problem" would affect, or be affected by these general categories.
If a black cat crosses my path it means I will have bad luck.
Codes are secret writing in which one word or phrase is substituted for another.
The Navaho code talkers of WWII used words like "whale" for "battleship". The substitution of a word for a word made the hidden meaning a code rather than a cipher. 
You will go, you will return, never you will die.
Meaning "you will go, you will return, never in war will you perish".