In order to learn, you have to work with experienced engineers, you’ll certainly pick up some methods from them.
You can also read books about GSM + GSM algorithms explanations from your vendor.
Now, regarding your problem, in my opinion, this is not really a problem if there is less call requests in one cell compared to another cell.
Even if you believe the amount of people in the covered area of each sector is the same, it might not be correct. You can’t know for sure : maybe the low populated cell has a coverage which is small, because there is actually another neighbor cell that also covers this area.
You have to check the number of SDCCH requests, the number of TCH requests and the number of TCH succesfully allocated.
If the nb of sdcch requests is low, it means you don’t have much subscribers in this area.