How hard will it be to transfer to the college of my dreams?

Hello folks. I would like to present to you my dilemma. Currently, I am a prospective student that attends Stevenson High School in Lincolnshire, Illinois. The problem right now is that I am very close to being done with my junior year, but I have the daunting image of having a not so excellent future. The reason being is that I know I will not be able to attend a top tier university of my choice. That being said, I have decided to make a plan. I will attend a somewhat good college, and after my freshman year I will finally transfer to the college of my dreams. My question for you is: How hard is it to obtain mostly A's and a few B's during freshman year in college, in order to transfer to a more advanced school? Please provide life experiences and factual support and evidence. Thank you.