definitely practice. language is not something u can master over a day like maths, it needs to be nurtured and instilled inside slowly. last minutes practice doesn't yield good results as u will speak/write more unnatural. any experienced examiner can detect this i think.

take it slow day by day and if u practice constantly on all skills (listening, writing, reading) I'm sure you can be better in one year. here's some of my way in improving english:

speaking: talk aloud by yourself everyday. if got a partner is better. this will make u less nervous and more confident when speaking in public. sometimes i feel myself nuts because i spoke aloud to myself too much. but the result is great i tell u

listening: doesnt have to be formal. just watch some english movies without subtitles and try to catch up to what they say. preferably british-based movies or dramas as we commonly use british english. american also can but choose ones with a quite proper language

writing: i can't say much, but i think a lot of reading can help. in fact, reading can help in all three skills mentioned here.

don't forget to buy books on muet too to help u with the formats and other stuff. hope this can help. i just taken muet last year's october. got band 5.