USAGE and word choice
University of Victoria (great campus!) usage guide

USAGE and style guides
The Economist magazine has a free style guide; although it is simple, it is solid.
Grammar Girl web site and podcasts (despite the name, a serious contemporary usage resource)
MIT’s ComDor Editorial Style Guide
Writing Technical Articles
Technical Writing
Strunk and White’s The Elements of Style online
The Coventry University Harvard Reference Style
Is here
Google can be a concordancer too:
You can ask questions at Stackexchange:
Google ngrams are a pretty cool tool:

USAGE: Concordance
1. Fantastic! Two great concordance samplers which can access the biggest and most famous corpuses (including the British National Corpus) are:
2. Laurence Antony at Waseda  University made Antconc, a free software for making your own concordance!

Journalistic style:  the 4-box system