Well, as someone who is currently within their junior year inside the major, I can give you some small tips that may help you, especially when doing undergraduate research. Basically, start getting ahead of the game by learning the main programming language being taught at your school. Since my school teaches Java and I had already knew C#, somewhat, I pretty much knew what I was doing, without the professor having to teach me much. Furthermore, make sure you understand binary, hexadecimals and all of that good stuff. Your introduction to computer science course, which is the first course you take before you even delve into the primary courses of your major, deal with all of that stuff. Then, after that, there is digital fundamentals, which is basically a harder version of that and deals with circuits.
To add on, math is going to be your lover, friend and companion for life. Start brushing up on your algrebra, a bit of statistics and some calculus. Don't play with your math. Programming is nothing but discrete mathematics and your major is a SCIENCE, which deals with a lot of math. Since you have to take a science, anyway, pick physics and not biology or chemistry. The physics course will help a lot. At least, it is helping me. I chose physics because I don't really believe taking a course in chemistry or biology will help much. But that my opinion.
If you really, really want to be noticed and obtain more opportunities, please learn everything before hand and make sure you understand more than your peers. I am talking data structures, algorithms and just being all around knowledgeable so others will feel as if you are the right person for certain opportunities and the likes.
For the time being, make sure you know what language you will be learning, understand the fundamentals and mathematics will be the keys to your success. Lastly, remember that Computer Science isn't just programming. There is a lot of theory evolved.
The courses are easy as hell. But, the content is vast. Just make sure you know what is happening, before moving on. It gets harder if you have no idea whats going on.