Struggling with aspect: When to switch to perfective verbs?

I have exactly 20 minutes every morning to practice Slovenian, and I keep hitting a wall with verb aspect. I understand the definitions, but knowing whether to use the imperfective or perfective form in a daily-life sentence during a conversation is destroying my flow. Since I don't have a tutor, I’m thinking about using Chickytutor.com to feed it my written drafts and see if it can point out why I'm getting the aspect wrong. Is that a good way to use my limited time?