Sentence structure is not that hard to get a handle on. Here's an exercise you can use to help you get a start on understanding the concept. Once you have a handle on the basics you can then move on to the more advanced stuff.
First write out what you want to say, then read it out loud like you are saying it to someone.
Take note of where you pause, that's a comma. Where do you stop before you begin another part? That's a full stop. Depending on the placement, a breath can be a comma or a full stop. You will quickly figure out how to differentiate here for effect.
Wherever you want to bring up a related but seperate entity, that's a new paragrah. Add capitals as needed and you're set.
Like I said this is just BASIC structuring guidelines, but it's a start and people will find it much easier to follow what you are saying, instant literary credibility, and they will begin to take notice.
