I am non malay, but i managed A2 in my Bm paper.
so what i did is....

1. Mixed with lots of malay ( to speak the language and put it into practise ) remember, dont speak broken bahasa.

2.Get a good peribahasa, simpulan bahasa dictionary. - this can helps you to do better karangan. It helps to score more points when you have nice peribahasa, simpulan bahasa and bunga bahasa in your karangan.
( this should give credit to my BM tuition teacher, who enlightens me on these )

3. enrol in a tuition centre for the language. They have lots of good exercise. test preparations for you. And you get some tips too.

4. Read Bahasa newspaper. Read as in, absorb how they composed those words, the sentences.

5. enjoy the language.

good luck !

'buku itu saya ambil ',- sounds more like spoken Bahasa to me.
while the ' buku itu diambil oleh saya ' sounds more like written bahasa.

Though i would compose it as " Saya yang mengambil buku itu " if i am to give confession.