PASTE AS PLAIN TEXT
Do not paste in content from another source without first stripping out the formatting. This is very important. When you paste in content from another source, it is common for hidden formatting code to come with it that can cause display and other problems for your webpage.
To avoid this problem use the 'paste as plain text' feature: 
-- Click in a text area and look for the little 't-in-a-box' icon in the text formatting toolbar.
-- Clicking this will open up a box where you can safely paste in your text. This will strip out any formatting that can do harm.
-- More info on using the text block: http://help.squarespace.com/guides/using-the-text-block

PARAGRAPH BREAKS -vs- LINE BREAKS
Text content doesn't look very good when there are too many odd gaps between lines of text. Keep paragraph breaks -vs- line breaks in mind while you are adding text:
-- To start a new paragraph use the Enter/Return key on your keyboard
-- To start a new line (with no space between it and the previous line), instead use Shift+Enter/Return

ARRANGE CONTENT BLOCKS INTO ROWS & COLUMNS
Squarespace V6 provides the ability to use the Squarespace 'Layout Engine' to place multiple content blocks on the page, and to arrange these blocks into rows and columns. 
-- Use more than one text block and drag/drop them to arrange them into columns to create more interesting layouts and make your text more legible.
-- This is especially helpful in your blog posts, so instead of being one long column of text, you can now break it up into blocks / columns / sections.
-- Learn more about arranging content blocks using 'Layout Engine' here: http://help.squarespace.com/guides/building-a-page-with-layout-engine