There are so many tips on how to improve your English communication and personality development but the most important tips are "practice" and "be yourself".
Tip 1- Always be polite, respectful, and honest.
Tip 2- Practice makes perfect. Practice at least 20 minutes every day in front of a mirror or video recorder to improve your English communication.
Tip 2- Watch English movies, listen to English music and talk with friends.
I believe that understanding the culture of a country is very important because you can't force yourself to change someone's culture. If you want to understand a culture you need to spend more time with people who live in that country and learn about their history, language and customs by talking with them.