Here is a short PPT presentation that gives a basic overview of using determiners. Basically, when it comes to determiners, what I tell my students is that there is one simple rule that they must follow or risk my unending wrath:
A SINGULAR, COUNTABLE NOUN MUST ALWAYS HAVE A DETERMINER BEFORE IT!
There are a variety of determiner types, quantifiers, numbers, demonstratives, possessives and articles. Of these, we most often focus on articles because that is where students have the most trouble. However, I think that by showing the concept of determiners all together it helps them better understand what is going on and allows them to be a bit more accurate grammatically.