In most cases, the distinction between the forms of the genitive and accusative case presents no difficulties: one only needs to pay attention to case endings.
If the endings of both forms coincide, you need to act on the following algorithm.
If before you an inanimate noun,Then you should ask a question for this word. Nouns in the genitive case answer the question "what?" And are combined with the word "no". The nouns in the accusative answer the question "what?" And are combined with the word "see". For example: I put on (that?) Coat - Accusative case, I go without (what?) Coat - genitive case.
If before you an animate nounMasculine gender II declension, then you should substitute for it any word I declension and look at its ending. For example: shot a wild boar = shot a fox (ending -y - accusative case), frightened a wild boar = frightened foxes (ending -y - genitive case).
If you have an animate noun before you,Standing in the plural, it must be replaced by an inanimate noun in the same form. For example: I love people, I love (what?) Letters - accusative case. I love the sincerity of people, I love the sincerity (of what?) Of letters - the genitive case.