Formatting
Reduce the point size and line spacing slightly.
Indent the text block between half an inch and a full inch on the left side, and optionally the same on the right. Or on the web, about 2–5 ems.
As with first-line indents, make the side indents large enough to be noticed, but not so large that the line length is too short.
Don’t put quotation marks at the ends—they’re redundant.
Block quotations are sometimes unavoidable. Sometimes, accuracy demands extensive quoting.
If you want readers to pay attention to quoted material, edit it carefully and integrate it into the text. Don’t just shovel it into a block quotation.