There are several steps to developing an assertive response.   We’ll use the example of Shelly the roommate to elaborate on each part.

1. Determine Your Rights Within the Situation.
   
   I have the right to be treated with respect, as does anything that belongs to me.
   
2. Plan a Time for Discussing What You Want.  Of course there will be times when we can’t always do this.  However, when we can, we should plan on a time and place where we aren’t likely to get distracted or interrupted.
3. State the Problem. Here we should always address the primary person we’re involved in the conflict with and talk about how the problem effects us.
   
   Shelly, I’ve asked you several times not to use food in the kitchen that’s not yours and not to eat leftovers that don’t belong to you, but these things keep happening.
   
   It’s a real inconvenience for me when I get ready to cook something and find you’ve used the ingredient I needed.   And it makes things hard for me if you eat the leftovers I’d planned on eating, especially if I’m in a hurry to eat before I leave again.