You should re-read your entire paper several times before you turn it in. If you haven't even looked at your introduction for some time, it may need some brushing up before it flows well with the rest of the paper. It would help to have a friend or classmate read over your paper to see if someone not as familiar as you will find problems you may miss. There are a number of other specific recommendations as follows:

Title: update the title to reflect what the paper turned out to be

Abstract: Rewrite the abstract (or write it) so that it summarizes the results of your research. If you already had an abstract, change the tense from future to past. Check the APA manual for contents and length of the abstract

Introduction: Change the tense from future to past. Update the hypotheses (make sure that they align with your scales and what you actually did).

Methods: Change tense from future to past. Ensure that you have construct validity evidence (i.e. internal consistency, temporal consistency, convergent validity, discriminant validity) for each and every scale

References: Check references against the citations, every citation should have a reference, and every reference should have a citation in the text.

For some classes, there are rubrics, or grading guidelines, that the instructors use for grading your research project.  It is useful to read rubrics early on in the writing process to make sure you are following all the requirements.  It is also good to compare your final product to the rubric to get a sense of whether you have all the necessary components.  As well, some rubrics are very specific about details and some give you general ideas about writing style.  Below are the links to available rubrics