If your friend is a weak speaker in English you probably need to motivate him to practice english regularly if he really wants to study abroad.English is the main language he will have to speak english everywhere.Remember that he is wanting to study abroad, in a new country,culture and language. So he will have to use english to convey why he wants to study abroad and in which skills he is good at.So, Tell him to practice vocabulary, go through dictionary and try to pronounce new words.To speak english wherever whenever possible and get a full practice of it before he goes for an interview.Also tell him to maintain a diary.With regular practice he'll surely improve his speaking and writing skills and will get ready.