Before recording a journal in a ledger, you should know where to record the ledger. You should know the amount that you record are in right account. Therefore, an accountant should analyze the transaction that affect the business. Not all transaction will affect the business, For example, contract, agreement, etc.

The accountant should be clever to select which business event could be record at ledger. The accountant should analyze any transaction which influence asset, liability and equity ownership. Certainly, the accountant should know the type of asset, liabilities and equity.

Each transaction will affect two different posts or double entry accounting that is useful to check the numerical entry of accounting recording. The amount of the asset should be same with the amount of the liabilities and equity. If you find the asset and liabilities do not match, you should check the journal entry. 

Example: a shopkeeper buy a $ 1 pencil with cash (assumption: there is no tax charges such VAT, GST, etc). The shopkeeper take the money form shop cash and the pencil will be used for the shop administration. This transaction affect two asset type i.e. cash and expenses. We can record the pencil into inventory because we use pencil as production factor. Since the price of pencil is low, we can post them at expenses post.

If the shopkeeper buy the pencil with debts, you should change the journal.  One dollar should be recorded at debt ledger, and one dollar is also recorded at expenses ledger.