There's some great courses available on websites such as Coursera and EDX. These are university quality courses and are provided free of charge typically, so long as you don't choose to pay for a certification. Here's a few examples of these courses (I haven't tried any of these because I am a native speaker, but the other courses I've completed on these sites have been quite good).
https://www.coursera.org/learn/speak-english-professionally
https://www.coursera.org/learn/careerdevelopment
https://www.coursera.org/learn/grammar-punctuation
https://www.edx.org/course/english-grammar-and-style
Watching videos, TV, movies can also help you to grasp conversational nuances and learn new words and phrases. Reading news articles and books in English will also be helpful. If you can read even one article a day, it can help you greatly in the long term. Conversing with native speakers online is also a great way to learn the language. Nothing will help you more than speaking out loud and messaging with native speakers. Finally, if you want to learn vocabulary and basic grammar in a game-like manner, you may want to try out Duolingo. Keeping daily streaks going and climbing up the ranks serves as a great motivator, and it helps you to see your progress.
Hopefully some of those suggestions and resources will be useful. Best of luck with learning English!