The links below will help you to find out more about separable verbs. They are all clearly written, with examples and explanations. The easiest ones are at the top, the hardest at the bottom.
♥For a clear and straightforward explanation: An account with examples and explanations in English at german.about.com
♥Another clear and helpful explanation: This one is from the BBC website and provides many everyday examples
♥An explanation with examples and some fairly challenging exercises: Separable verbs and exercises at the Lingolia website
♥Online exercises from Schubert Verlag (a publisher of German textbooks) offers many excellent online exercises with immediate feedback about whether your answer is right. All you need to do is click on the traffic light beside the question to read the correct answer: Schubert Verlag Online Exercises – Separable Verbs
♥ Explanations and examples entirely in German at Mein-Deutschbuch: For a detailed German account of separable (and inseparable verbs), with many examples written in German, go to this site: Mein Deutschbuch – Separable Verbs
If you really want to challenge yourself, you can download this PDF on separable verbs at the link below and read it slowly. Fortify yourself with a cup of hot chocolate and a big dictionary. The file is entirely in German, so it is not for the fainthearted.