Listening skills are imperative for students and everybody, especially non-literate ones, should be given more listening than speaking practice. It's important to speak as close to natural speed as possible, although with beginners some slowing is usually necessary. Without reducing your speaking speed, you can make your language easier to comprehend by simplifying your vocabulary, using shorter sentences, and increasing the number and length of pauses in your speech.
Those that don't require learners to produce language in response are easier than those that do. Learners can be asked to physically respond to a command or participate in real time conversation.