Your email should:
When asking for a research opportunity:
state specifically your interest in that research group (you need to read the professor's website)
explain why research is important for your goals
ask to schedule a meeting or say that you will be coming to office hours
Subject: Research Job Op
My name is Name and I am a major in Major. Is there space in your lab for an undergraduate? If so, what is the pay rate and the hours?
Subject: Possible undergraduate research opportunities
Dear Dr. Professor,I am a (year, major) at (university) and I am writing to ask about opportunities for undergraduate research in your lab beginning (time period). I have conducted undergraduate research on (topic) with (names) in (program or class). (Expression of interest in the topic). I would like to continue a path of research on (topic) and would ultimately allow me to (career goal). I am especially interested in your previous work on (describe a paper or talk).
I have attached my CV and unofficial transcript to this e-mail, but if there is additional information that I have not included that you would like, I would be happy to provide it to you. Thank you for your consideration.