You cannot totally predict bitcoin price but due to bitcoin being very volatile, rumors or news can greatly affect its price. A negative news will make its price decrease while a positive news can make its price increase. There are key events that would make you speculate where the price will go in the next few days or weeks like what is happening nowadays. Due to the incoming bitcoin hardfork, there are more people who would hold or buy bitcoin so that they can have bitcoin gold as well and for this reason, we can expect bitcoin to increase.
Bitcoin is actually a lot easier to predict than most other markets. If you look at a long-term chart of Bitcoin you will see that it always goes up exponentially, followed by long-term decline and then another exponential rise. This has happened over and over since 2012 and before. If you buy in when the price drops, you are very likely to multiple your money by 3x or more within a few years.