Most professors are working on a research project for which they need assistance from eager students. Being a Research Assistant to a professor generally means setting up a lab, setting up experiments, writing research papers, performing experiments, and presenting their findings, conclusions, and recommendations. In short, you will be involved in a particular faculty research project, which will also serve your research topic.
Some universities do not have an application process for the position of Research Assistant. Students, in this case, are selected by the teacher. For the rest, you can apply for the position along with your college application and can hold the position only after your first semester. Similar to a Teaching Assistant, you can expect a partial or full tuition fee waiver. Apart from the waiver, students earn a generous stipend as well. You can expect to earn anywhere from $500 to $1500 monthly working for 15 to 20 hours. The pay also depends on the number of hours you work and the kind of work allocated to you.