If I **were** you, I **would not spend** all my pocket money on cosmetics.
*Explanation: This is a second conditional. It describes an unreal present situation and its hypothetical result. We use 'were' (for all persons) in the 'if' clause, and 'would + base form of the verb' in the main clause.*
*Перевод: Если бы я был тобой, я бы не тратил все свои карманные деньги на косметику.*