Target your program towards the age level of the students you are encouraging to read. What might work for students in Grade 1 or 2 would likely not encourage independent reading in students approaching middle school. For the youngest grades you should have a good mix of children's books and books that are designed to help students learn to read. For those approaching the end of elementary school, there are many good series of books aimed at children, such as the Harry Potter books. Junior high and high school students will need a mix of fiction and non-fiction, and should have exposure to full-length novels. Look for bestsellers in the young adult market to keep current if possible.
Connect your students with books they might be interested in reading. This might mean that you need a large reading library in the classroom. You could also create recommended reading lists based on the students' interests, reading abilities and the books available in the school library. For example, if a student is interested in speculative fiction, you could give them a list of books to choose from such as the "Lord of the Rings" trilogy or the "Dragonriders of Pern" series. Someone interested in detective fiction in junior high should have perennial favorites like Nancy Drew and the Hardy Boys pointed out to them. Use your greater knowledge of available books to help guide students towards reading that you think they would enjoy, but ultimately leave the decision to them.
Allow students to suggest books for their own independent reading. Require that the students suggest books to you before they want to read them so that you can approve them. Research the book online to make sure it does not contain any material that you or parents are likely to find objectionable, such as excessive violence or foul language, but approve as many books as you can. Students who can direct their reading into areas of personal interest will likely start to enjoy reading more.
Require the students to complete some kind of regular activity based on their independent reading. A good activity is journaling. Have the student complete a short journal entry after every reading session to document their thoughts about what they read, as well as how challenging or simple they found the material. Try oral sharing sessions, where the students share with each other about the books they are reading.
Create a log where you can track the books students read as they complete them. Past books they've chosen might inform suggestions about future reading and will help you evaluate each student. For instance, you could offer to award bonus marks to students that complete a certain amount of reading, as long as they can turn in a short piece of work proving that they did in fact read the book. A simple questionnaire about the characters, story and setting of the book is usually enough.
Have students complete a larger assignment based on a book they read during independent reading. This could be a book report or an oral presentation on a book or writer they enjoy. When a student knows they are going to have to do something for marks later on, it can help them stay motivated and focused. You could also do more creative projects such as asking students to dramatize and film a scene from a book that they particularly enjoyed.