McKinsey PST is the hardest one, so I recommend starting and tracking your prep using PST materials. If you have good results with PST, other tests are not a problem. For this you can:
• Buy Viktor Cheng test prep program - the best materials I've seen so far.
• Practice your math.
Do the 2nd test and check the score
Also, you can find a good number of PST test online
For the BCG test you can prepare the following way:
1) Keeping your math trained with GMAT exercises is always a good idea. Free resourced can be found online, for example:
- https://www.mba.com/exams/gmat https://www.mba.com/-/media/files/mba2/assessments/2018/gmat/gmat-handbook-2020-07-10.pdf?la=en&hash=9DCAD3E9A43EEE7B520C84327FBEC6F399A72D82
2) Also, tests that usually are for investment banks (with graphs analysis) are useful. Free resourced can be found online, for example:
3) Official BGC Potential test examples: https://www.bcg.com/careers/path/consulting/practice-interview-cases.aspx