Restate succinctly and clearly the points you made in the paper. Briefly summarize your main points without being repetitious or going into too much detail on each separate point. Explain every point with only one sentence.
End with a statement or question that gives perspective to the subject of your paper and thesis statement. Make a connection between the subject and the broader world. Let the readers know why they should care about your subject.
Mind the structure. The structure of the conclusion is just as important as the structure of the main body. If you are an inexperienced writer, a good way to avoid repeating yourself is using signpost words such as "firstly," "secondly" and so on, and build your conclusion around them.
Don't bring in new information. Conclusions are not a place for new information. Whatever you had to say, you should have already said in the body of the research paper. When you get to the conclusion, all that's left to do is wrap up.
Give your work a sense that it's done. This can be achieved with an appropriate question, a witty statement, an interesting metaphor or another emphasis on why the topic of your paper is an important matter. Ensure that any statement you make is consistent with the tone of the rest of the paper.