Teach the infinitive
Every time a new verb is presented, I hover over the word and click "Conjugate" to see the infinitive. I would really like it if the infinitive was presented with new verbs, even if it's just in the hover-over menu directly. Otherwise, I sometime get to the end of a lesson and look at the list of new words I learned and think "What's that?" until I realize it's the infinitive of one of the verbs. Also, by giving us the infinitive initially, it becomes easier to conjugate when needed later on.