This may sound odd to someone currently struggling with algebra, but one of the best ways to learn a topic is to try to teach/explain it to someone else (who, presumably, has little or no knowledge about the topic). As an example, would you be able to derive the quadratic formula or prove the rational root theorem to someone else?
This method might feel intimidating at first, but the advantages of this method include the fact that it forces you to have a solid understanding of the topic, as well as improved communication skills (which is not often covered well in the standard HS math curriculum).