In order to increase your chances of passing any exam focused on grammar you should:
1. Know and understand the structure of the exam
How many parts does it consist of?
What do you have to do in each part?
How much time do you have?
Will you have any additional time to transfer your answers to the answer sheet?
2. Try to understand how the little bits and pieces of English grammar work. I know it is a daunting task but you will not escape it!
3. Find a good self-study grammar reference book and do it!
4. Find a good YouTube channel/podcast/blog that explains English grammar in your native language.
5. Try translating from your native language to English but do it with someone who can immediately correct you!
6. Keep track of your mistakes. If you notice you make the same mistake over and over, focus on it!
7. Practice one grammar structure at a time
In the exam remember to
read every task carefully
not leave any gap blank
not spend too much time on one exercise when you are not sure of the answer; move on to the next one!
ONE LAST TIP: Practice makes perfect!