I will second that, I know a lot more about imperfekt verbs than some Germans, I was using them today and explaining to them what the difference was haha, but again, if you want fluency....vocab, vocab, vocab! Another time I said gewollen cause stupid me couldn't think of the past tense of wollen and they understood it fine even though it was a bit weird. If you don't know a past tense version of the verb, adding a ge in the front or if its like abhauen (to scram) put the ge in the middle, abgehauen.