it would be useful to know which test you are preparing for, since, as Harri mentioned, tests can actually be pretty different in different consulting companies.
Each test has its own criteria, and in general the best kind of preparation is to prepare in advance on the same type of test – for all of them you should be able to find free and/or paid version online.
Some general tips on analytical/numerical tests that can be useful are:
- Commit to a time for each question, and go on if you surpass that time. If you do not set discipline, you will end eating too much time for some questions (these tests sometimes are actually structured to have some questions it is better to skip and review at the end). If time and test allows, you can then go back to the questions at the end.
- Practice math before – it is normally a key component of all the tests. You can find a lot of free and paid resources online for mental math. The specific type of best resource depends on the test you have to do.
- Use elimination process when in doubts in multiple choice question
- If needed (eg PST and Potential test): Practice graph interpretation
- If needed (eg PST and Potential test): Practice quick reading of key information only
Finally, it is important you understand in advance if you get penalized for wrong answers (eg Potential Test) or not (eg PST), since this may change your strategy.
Hope this helps,