Practice, practice, and practice. May I ask what English test are you planning to take next month? Is it the IELTS or the TOEFL? You should learn the format of the test first to familiarize yourself with the test.
There are a lot of resources you can find online. Here are some resources that might help you:
If you have questions, feel free to explore the forum.
Helo! well you need to study. look at your question :
I plan to take an English test next month but I NEED to improve my English writing how do I do it?
READING IS A WAY TO IMPROVE YOUR WRITING and I'm afraid you need to study a little bit .
a before consonants = a desk , a pen
an before a vowel = an apple an orange
plan - this verb usually you don't say: I'm planing to x it's wrong
you PLAN TO do something = I plan to go to London
The same with : like to - would like to - want to - hope to
Hope it was a kind of help. keep trying :) HAPPY EASTER