What precautions are necessary while using income method of measuring National Income?

Following are the necessary precautions that should be taken while using income method of measuring National Income:
(i) Income from transfer payments should not be included, (e.g. Rs. 5000 given to you by your father as your birthday gift).
(ii) Income in terms of capital gain should not be included, (e.g. gain from the sale of old property, shares and bonds).