Yes, I know, that is your question. Why... Why, do we, innocent learners of Italian, unaware pursuers of that knowledge, have always to go through the frustrating process of figuring that out? I understand, folks. I really do. And this is the reason why I am offering some very useful and to-the-point tips in order to make a well informed choice. Perfection will come only with practice, so right now just follow what I say and you will lay down some strong foundations that will help you then in the future.
Ok, let's go!
The very first thing you need to know are some essential grammar notions which are crucial in order to understand the process. They are listed and explained in the following boxes.