One thing that I find to be the hardest for me when RPing is my language barrier. I'm not talking about the basics because I get the basics of the English language. 

In my own language I know how to make a sentence sound kind or condescending or indifferent without having to add how it's said, whereas in English I'm often stuck looking for the right words to make it sound like something said by an actual human being. Often I also just don't know how to phrase something to my liking. I can make the sentences, I can get across what happens, but it just doesn't have the feeling I want it to have. 

It's really goddamn frustrating sometimes.