A common mistake that many English learners, as well as native English speakers, make is the use of If I was ... rather than If I were ... for the unreal, or 2nd conditional, form. In fact, this form is so commonly used that many accept it as correct. This is a case of descriptive, rather than prescriptive grammar. However, there are instances in which If I was ... can be correct. Learn the rules and the exceptions to If I was / If I were.
While you are learning this form, you might want to brush up on the conditionals by reviewing conditional structures and taking a conditional form quiz. Teachers can use this guide on how to teach conditionals, as well as this conditional forms lesson plan to introduce and practice the first and second conditional forms in class.