Pictures, gestures, sounds, acting and also using some English (or any intermediary language that at least some of your students know). Writing English translation on the board will help. Especially for some abstract words/ideas or grammar terms in the beginning when they're still unfamiliar with the system. Even if they don't speak English, they can use online translators at first lessons which will help. And also if someone understood something, they should be allowed to explain to the others, providing they speak an intermediary language. And last but not least, I think creating a sort of routine every lesson might be useful. The most difficult is to survive the first lessons, it'll become easier later.