Christa A. answered 05/10/19
Columbia Publishing Course Alum, Writing Coach + English/ESOL Tutor
There are a lot of ways to increase English language skills, but they're mainly broken down by reading, speaking, listening, and writing skills.
Your learning style and current skill levels will determine which of these you should focus on, but there are some great ways to work on a few of these at a time.
You can listen to an audio book and follow along in the print or ebook version to increase reading and listening skills. You can find a dialogue partner, someone to speak with in English on a regular basis, to improve your speaking and listening skills.
You can read bilingual texts if your reading levels are in the beginner stage. Short story and poetry collections, as well as children's books, are great for learning new languages, because they're shorter and you can focus on smaller pieces at a time--and these will also help give you cultural context. You can also find some short story collections meant for learning, which will include questions at the end so you can practice your writing skills. There are some great writing prompt websites that will help you find interesting topics to write about if you want to practice personal essay/creative nonfiction or fiction writing, and you can also find some good personal essay/creative nonfiction prompts by looking at college application prompts--many colleges list their entrance essay prompts from previous years on their websites.
There are plenty of other tips, of course, but I hope this helps give you a start!