Is there an easy way to understand Korean particles and verb endings?

Question

While learning Korean, one of the most difficult parts is the various uses of particles and verb endings. Especially, it is often confusing to know which particle to use in certain situations. For example, I know that the expression '**나를**' is used when someone is doing something to me. However, every time I try to find such explanations using apps, it's difficult because I have to read long explanations of more than 3 paragraphs just to understand one particle.

Do any of you who are in Seoul know of an easy way or resource to explain particles and verb endings? If there are any Korean language study groups for foreigners in Gangnam or Hongdae, or recommended Korean textbooks, please share.