A number of things will help you learn a new language. Reading simple books in that language such as those written for children and teens. Reading online magazines and newspapers is another, as those are written in a simple manner. Watching documentaries on YouTube in the language you wish to learn will also help. Watching television programs and films in that language will help one learn conversational forms of the desired language. A source for public domain downloadable books is the Gutenberg Project: http://www.gutenberg.org I hope this of some value, I hope to put together a listing soon of books, films, and such available on my web site to better aid in this.

Firstly, the sentence is wrongly structured, it should be " what is the best way to learn English that is entertaining" , and secondly, try reading famous English novels/plays or watch famous TV dramas or movies.

Erin...thanks for correcting my sentence :) Thank you guys. It is really useful advices.

I am learning french and I found that there are a lot of cool instructional videos on Youtube (free) and also podcasts on iTunes. These have helped me a lot with french and I don't find it boring at all. In fact, I listen to these videos and podcasts in the car while driving or while cooking dinner. Hope this helps.