Sadly, there is no real way to determine which courses will need to be lotteried until shopping week. That said, there are certain important courses that are limited/lotteried nearly every year. For example, research methods courses are almost always limited (this is due to the need for computer and other facilities that only hold a limited number of students). For this reason, research methods courses often tend to be over-subscribed. We therefore strongly suggest that you plan to take one of these courses before your senior year. You can save yourself a senior year headache by taking these courses early.