Contrary to what a lot of people say, practicing IQ tests really does work. If during an assessment you are confronted with an IQ test and have done similar tests before, you will score better in some areas.
Of course, to a certain degree your IQ is a given and by practicing you will not all of a sudden score much higher. However, an IQ test always is a snapshot, and the result also depends on the time you take to perform the assignments and, for example, on how nervous you are. It is exactly these factors that you can improve upon by practicing IQ tests in advance. You will know what is in store for you, and because of that will not be as nervous. In addition you will be able to complete the assignments a little bit faster because you recognise the question types.
An example of a component frequently used in IQ tests is the number series. You will be shown a series of numbers and get the assignment to enter the missing number. By training such number series you will quicker understand the logic behind the series, because a number of these series are used quite often and because you train yourself how to read these series.
The same thing applies to series of matrices that only differ slightly and where you have to enter the next matrix. By practicing these series, you will usually recognise the solution faster, because your brain already has an idea how to solve this.
Practicing IQ tests is something you should just do. Take a lot of tests and try to find out which components are causing you trouble. Practice those components more than the others and try to not just solve the problems, but to find the actual reasoning behind the solution. It is not about knowing a lot of assignments and solutions by heart, but about understanding the questions so you can more easily answer similar questions in the future.