This style guide is obviously intended for use by journalists at the Economist; however, I think anyone who wants to make his or her writing gooder will benefit from it. Among the guide's several sections is a section on common solecisms (grammatical mistakes). Here are a few examples:
Apostasy and heresy. If you abandon your religion, you commit apostasy. If that religion is the prevailing one in your community, and your beliefs are contrary to its orthodoxy you commit heresy.
Factoid: something that sounds like a fact, is thought by many to be a fact (perhaps because it is repeated so often), but is not in fact a fact.
Only. Put only as close as you can to the words it qualifies. Thus, These animals mate only in June. To say They only mate in June implies that in June they do nothing else.
Sensual means carnal or voluptuous. Sensuous means pertaining to aesthetic appreciation, without any implication of lasciviousness. [For all of you Animal House fans out there].