Body copy should be as transparent as possible. In most cases, this is achieved by using a typeface, one that doesn't draw undue attention to itself. This allows the message to emerge. Whenever possible, choose a familiar serif typeface. Numerous studies have shown that serif typefaces (like Garamond, Palatino, Times Roman) are easier to read than sans serif typefaces (like Helvetica). This is because the serifs guide the reader's eyes along from letter to letter.
Consider setting body copy text flush-left/ragged-right. Flush-left alignment is characterized by equal word spacing and lines of unequal line length. This creates interesting pools of white space at the end of each line which further opens-up each line. The equal word spacing of flush-left/ragged-right type allows readers to establish a rhythm, making their job easier. Always hyphenated flush-left/ragged-right text, however, to avoid extremely short lines followed by very long lines or lines that form diagonals or other shapes along the right margin.