Paragraphs are your friends. As are the innocent comma, the oft-neglected semicolon, and the exclamation point (not to be confused with 1).
It takes but two keystrokes to begin a new paragraph. Either the enter and the tab keys, or the enter key twice. Paragraphs are helpful in that they don't make my eyes cross when trying to read your fic.
As soon as I see a fic with no paragraph breaks, I hit the back button, no matter how wonderful your writing may be.
So, in closing: PARAGRAPHS. USE THEM.
Feeling helpful today,