Списьмом : ) you have received a letter from your english-speaking pen friend arthur. 's my best friend's 16th birthday party next week, but i don't know what to buy him. i need your help and advice! have you ever bought a birthday present for a friend? what's the best way to choose what to buy? what if they don't like

Dear Arthur,
Thanks for your letter. You asked me if I have an advice for you, well I have.
  First of all, you should know what your friend likes. For example, if your friend is fan of pens, pencils etc. then buy him unique pen/pencil. If your friend likes LEGO or toys, then buy him LEGO set. If your friend fan of Star Wars, then buy him a glass or T-shirt. But for everything I put in this letter upper can walk into shadows once I'll tell you, that best gift on birthday is book. Interesting book... With surprise inside of it. For instance, money. You can put $10 inside of the book. It'll be good surprise for your friend.
  Well, anyway I have to go now. I'm looking forward for your letter.

Bye,
Someone (тут должно быть твое имя)