First go through the TB. Go to individual ledgers if possible and try to ananlyse the entries if it has been passed in the correct account ledgers.Further if the amount is inconsistent get a clarification to ascertain its correctness.
Basically enter into P & l A/c 1.Start analysing the correctness of each account may not be each entry once you get the feel of accounts 2.Check the applicability of TDS for expenses and ascertain if the same has been adhered to 3.Applicability of VAT, service tax and input whether it has been availed and claimed. 4.Whether any expense has been overstated or understated. 5.Whether the expenses have been accounted under the correct head of accounts. These are the synopsys based on which the logic can be built on and Ledger scrutiny can be carried out