Sorry, you got the wrong end of the stick, again!

Q: "What is most widely spoken language in the world?"

A: "Bad English"

Even though this is a joke, it is also not far from truth. Sadly, too many people these days underestimate the complexity of learning a language, especially English. "English" we learn in schools is quite the opposite of what English actually is.
It is enough for communicating about everyday stuff or for asking for directions if you're in a foreign country. People will understand what you are saying, but will you understand what Americans or Britons are telling you?

Let me give you an example:

You have a survey on whether people like horror or action movies more.

If you come across a stranger, he will probably say something like:

"Action movies are, in fact, my favorite. Horror movies, on the other hand, are too unrealistic for me and I don't like them". 

Perfect,you understood what the person said and you can continue with your survey.

An English native speaker will say something like: " Horror movies leave me cold and action movies are not my cup of tea." Hmm, does that mean that this person watches horrors tucked up with few blankets because the temperature get lower as movie is coming to an end? And what does tea have to do with action movies? Any suggestions?

Even though, the grammar is not very complicated, it's the phrases and hidden meanings behind them that give people hard time understanding the language. If you change only one adverb in phrasal verbs, you will get totally different meaning. For example, make out means to see or discern something, especially with difficulty. Make up means to compensate for. It is maybe easy to learn a difference between theses two phrases, but there are numerous phrases that are written in the same way, but have different meanings. Let's take make out for as an example. Firstly, it can mean to see or discern something, especially with difficulty. Secondly, it can mean to hear something well enough to understand it. Thirdly, it can mean to achieve a particular level of success.
(source: http://idioms.thefreedictionary.com/make+out)
Here are only few out of many different meanings this phrasal verb has. My point is, that it is very easy to get the wrong end of the stick while talking with English native speakers. Therefore, be careful and read carefully and conscientiously. If you didn't understand what the person told you or if you hear something that sound like a metaphoric phrase, ask. Don't just nod your head as you'll never improve.

Thankfully, the Internet is full of useful sites that can help you improve your English. So, if you don't feel confident about your English, I recommend you use these helpful sites on a daily basis. You can hear news every day on a different accent, you can read and write and have fun throughout.

List of useful links:

Dictionaries! Please, check if you're not sure about a certain word.
Cambridge Dictionary
Merriam-Webster
Longman Dictionary
Oxford Dictionary
Vocabulary.com

TED talks (short presentations with clear pronunciation and very interesting topics)
Missed in history
How stuff works?
English for those who already speak it 
Hogwarts is here (Finally, for all HP fans, here's a website where you can actually learn all the subjects from HP, but most importantly, you read books and write essays and you also get grades. Explore it on your own, I won't spoil it for you)