To speak like writing skills and to use many properly sophisticated vocabularies. 

Facing difficulties in pronunciation is a natural one.We  can make differences in the meanings of two similar 'looking' words by its context.

TIME plus MOTIVATION

Time is my most concern because people have to work or study for thier living. What is more, motivation is also an important issue to be concerned, yet, motivation can sparked or inspired by your own ambition,  so as a consequence, I am convinced that time is the most terrible enemy in front of learning English.

Spelling and pronunciation are problems for even native speakers of English. You have to be well-studied in order to do these correctly. Due to all of the influences of Celtic, Nordic, old German, old French, latin, greek, and some modern influences (such as spanish in the United states), it is impossible to trust the spelling to allow you to properly pronounce the word. :/

The hardest parts for me is when I heard confused words that sounds alike but have very different meanings, such as accept except, aloud allowed, pour pore, desert dessert, currant current, defuse diffuse, etc. I really hate when I had conversation with foreigns sometimes I got to say "Sorry, can you repeat? Sorry?? What do you say??" and the most embrassing thing was "Can you spell it please?" Uff.. x(