Students who did not gain acceptance to their first choice colleges as a freshman last year sometimes contemplate trying to transfer into those colleges as a sophomore for next fall. That can be tough unless the student has taken the right courses and done well in them.
Looking at it from the standpoint of the prospective transfer school that did not offer admission to them last year, the things most likely to convince them to make an offer this year is whether the student took a normal full time load of freshman courses and did well in them. The things that will fail to impress them that the prospective transfer will be successful at the desired transfer school include dropped courses, grades below B and an overall GPA (at their current school) that is average.
The thing that always surprises me is that students with average grades at a less challenging school want to transfer to a more challenging school when they are clearly NOT READY. They likely will reach an appropriate stage of readiness with one more year at their current school, but average grades as a freshman at a school that is easier than their desired school is a warning that they need to do some more preparation before trying to compete in a more challenging setting.