1. Self fulfilling a prophecy.
When a person who knows the prophecy causes it to take place then it can be called a self fulfilling prophecy. But this can be the case only if all aspects of a prophecy can be engineered by the person or people desiring its fulfillment. An example from the Bible would be when Jesus rode into Jerusalem on a donkey on the very day it was predicted that the Messiah would come. Jesus knew the prophecies and chose to fulfill them by his actions. But does this disqualify the accuracy of the original prophecies?
If these were the only prophecies about the Messiah then they would certainly be disqualified. Jesus chose to ride in on a donkey, he also chose the correct day. Any one could have done that. How many other would be Messiahs rode in to Jerusalem on that day? If that were all there were to being the Messiah then anyone could have fulfilled it. But there were a number of things required that Jesus could not have guaranteed. The unbroken donkey colt would have to be ridden. The crowd had to declare that he was Messiah and King. The religious leaders had to reject him. Jesus specifically chose several aspects of the prophecy that the Messiah was to fulfill, but he could not have engineered the rest.
Also there were hundreds of prophecies, many of which were out of Jesus' control. When Jesus was born the wheels preparing for the Messiah had been in motion for well over a thousand years. But because there were certain prophecies that Messiah had to do and do successfully. Jesus had to deliberately fulfill them, giving sight to the blind for example. So even if a prophecy can be deliberately fulfilled it can be considered authentic if other non-self fulfilling prophecies were contingent on it or related to it. If we eliminate the few prophecies which the prophets themselves caused to pass, there are still many hundreds left to consider.
2. Fake it.
Imagine someone writing a prophecy about an event that had already occurred and then claiming it was written by someone else at an earlier time. This act of fraud is often claimed of the Bible, but has yet to be shown true. The Old Testament was finished 400 years before Christ and translated into Greek 270 years before Christ. The prophecies contained in scripture about Christ therefore could not have been written after the fact as some claim. There are many other prophetic events that occurred well after the books that predicted them were written, events that occur even after the most liberal dates given by any scholars. A good example is the book of Daniel. Liberal scholars have attempted to assign it the date of 165 BC because the book contains an accurate history of the Greek empire up to that point in history. But Daniel lived in the 6th century BC. So since the scholars don't believe that prophecy is possible, Daniel must have been a 2nd century BC impostor. The problem is that the book of Daniel continues to accurately predict events that occur after 165 BC. So how did an imposter writing history after the fact accurately predict events and dates in the life of Jesus? Prophecy can be faked, but the Bible is authentic.
3. Revise the text.
This would be an attempt to alter existing documents so it looks like they were originally predictive. This only works when you have a few copies. Once you have many copies the changes have to be made to all existing copies in order for a revision to go unnoticed. We have thousands of copies of the Bible, and while there is a small amount of disagreement, mainly spelling, very few have any impact on prophecy in the Bible. Remember also that the prophecies of the Messiah were in the Torah, the Jewish Holy Book, what we call the Old Testament. They would have had to agree to alter all the existing texts to make it look like it contained the prophecies of the Christ that Jesus fulfilled. There have been many archeological confirmations that the Bible we have today is in fact very close to the original. So while it is possible to revise or change a document, the evidence tells us that this did not occur with the Bible.
4. Be vague.
A prophecy could be written in such a way that the prophecy could fit a lot of things. Such as "A great leader will come and make war with his enemies." The Bible however is not vague. It gives names, places, times, actions and details. Bible prophecy was not written in such a way that it can fit anything. It is the real revelation of God to his prophets and it is not at all vague.
5. Predict the obvious.
When the enemy is at the doorstep of a city and your king's armies have been defeated, the citizens have been reduced to eating moldy bird dung and you say, "Very soon the city will fall." That's nothing more than what you might get in the morning news headlines. The Bible however does not make predictions of likely events. It often was very contrary to what people thought would take place. Consider the fact that in the nineteenth century many Bible scholars scoffed at the idea that Israel would ever become a nation again in spite of what the Bible clearly said. So to solve the contradiction many held to the doctrine that the Church had taken the place of Israel. Even today whenever they read "Israel" or "Jew" in the New Testament, they replaced it with "the Church." Its amazing how so many can still hold to this doctrine today even with the evidence right before their eyes. Another example is that the details of the crucifixion first appeared in prophecy five to seven hundred years before crucifixion was even invented. Sometimes things in scripture may seem obvious to us only because we live centuries after the fulfillment took place. The predictions in the Bible were not predictions based on the obvious, but on the truth.
6. Set no time limits.
This allows a prophecy to be fulfilled at any time after it was written. We of course assume that this would increase the likelihood of a prophecy being fulfilled because it has a longer time to happen. That's the same mentality that justifies evolutionary stories. But in reality, time limit or no, the longer a prophecy is left unfulfilled, the less likely it is to be fulfilled. Things change, civilizations, governments rise and fall. How could a prophet know what was going to happen centuries later based on what he could see then? The Bible contains both prophecies with a date and those with no specific date for fulfillment.
7. Cover all the bases.
If a lot of things are predicted then a few of them might actually happen. People are often impressed with the writings of Nostradamus because some of his predictions seemed to have come to pass. Yet only a small percentage of his prophecies can be tied to events that actually occurred, and those require interpretation. His prophecies would be a good example of covering all the bases and vagueness. The Bible does contain a lot of prophecy, but those prophecies are not ones that just proclaim random things or numerous possibilities that are likely to occur given enough time. The facts tell us that Bible prophecy hits it right on the mark, over and over again. Why else would the liberal scholars attempt to date, Moses, Isaiah, Daniel and many others as being written after prophecies were fulfilled? They know the prophecy is an accurate record. But their belief compels them to reject the idea that the records could have been written before they happened. The fact is that even the liberal scholars don't believe that prophecies are just thrown out hoping some will stick. The prophecies in the Bible are specific and they relate to the Bible's message. They are not just there for dramatic effect. They were made for a purpose and hundreds of them have been fulfilled. That's not the result of lucky guesses.