Classes Vs Individuals

OK, first stumbling block when trying to create an ontology. When should I model something as a Class and when should I model it as an Individual??

In general Classes describe a concept and an Individual fulfills that description. In other words the individual or instance is the realization of the concept described by the class.

Now, maybe it's just cause I am used to it, but in programming this is easy to comprehend as there is a very clear distinction between a Class and an instance of that class (or object). However I must say this distinction is not as obvious in OWL.

For the moment I am going with this general rule of thumb. If the "thing" is going to be either the subject or object in a triple than it will be an Individual. What that "thing" is, well that will have to be the Class.