Undergraduate research can greatly enhance a student's insight into his/her field. However, it is crucial to understand that this is very different from an ordinary course. Please keep the following in mind:
In most cases, you are producing code that people will actually use. So, it must be RIGHT. This is not like an ordinary course, in which a student gets most of the credit if the program is mostly correct.
Please adhere to the following rules (mostly pertaining to R):
Your code should have numerous clear, helpful comments. BEFORE you start writing a code file, place some comments at the top, explaining what the code is supposed to do, and in broad terms, how that will be accomplished. BEFORE writing a function, write comments stating the roles of the arguments, and the structure of the return value. DURING the process of writing a function -- NOT later, when you're done -- you should write comments explaining what the code is doing.
Finally, please sure to make continual forward progress every week. Yes, illness, work in your other classes and so on will mean that your progress will be less during some weeks, but do not give your research project last priority. If you do, you will have very little work done by the end of the quarter, and no one will be happy. :-(