Here is an excellent post from Everyday Sociology about how to study.
Don't re-read what you have already read. Close the reading and instead explain it. Recall it. Write it down. Explain it to someone.
Be careful of the Dunning-Kruger Effect and The Impostor Syndrome. To counter these, study with other people.
Try the Feynman technique:
Step 1: Pick a topic that you want to learn something about, and start studying it.
Ok, that seems simple enough.
Step 2: Mimic giving a lecture to a class. Here you can use that group of classmates again. Each of you could take a portion of the class materials and prepare a talk about it. Give that presentation to your group, and everyone should take notes. Step 2 is way to turn those reading groups into learning groups.
Step 3: Hit the books again. Now that you have a firm grasp of a section of the course materials, go back to the readings and broaden that sphere of knowledge. Perhaps use that slice of the course content to understand other facets of the materials.
Step 4: Simplify and use analogies. Now that you have that broader understanding, go back and break everything down further, but also think across substantive areas. For example, in an intro class you might look at how discrimination on race and gender are similar (and then how they intersect), or how we are socialized into different roles. But also: see if you can explain socialization and discrimination to your non-soc major roommate.