asks: "How do you make sure that your story makes sense? Most of the time, I get confused on whether my work is understandable for my readers. I usually drift off into my mind and get carried away, when I should be sticking to a main topic within my book."

It's easy to stray off course when we write. If you find yourself slipping into a thought stream and meandering in different directions, stop and evaluate what the purpose of that chapter is. You don't have to know how the chapter will end, but you should know what it needs to achieve. Here are some examples of possible chapter goals:

The main character gets to know the love interest better.

The villain is revealed.

Reader finds out why the main character only has one eye.

Reader gets a better feel for the people in the village.

The Mighty Axe of Ass-Kicking gets stolen.

With a purpose for the chapter in mind, you can periodically stop writing and ask yourself, "Does this get me closer to that goal?" If not, then maybe it doesn't need to be there.

As for making sense, this is where outside readers come in. Sometimes we, as story-tellers, forget what the readers don't already know. We know the story, and sometimes skip certain details by accident as we write. Beta readers or critique partners will help you point out plot holes or things that don't make sense. Writing is a solitary endeavor, but it actually takes a group effort to improve it.