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

Cohesion devices: logical connectors a.k.a. signposts a.k.a. connectives,
BTW: explore this site – it contains good things but the navigation doesn’t tell you much.

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
Journalistic style:  the 4-box system
You can ask questions at Stackexchange:
Google ngrams are a pretty cool tool:

USAGE: Concordance
1. Fantastic! Three great concordance samplers which can access the biggest and most famous corpuses (including the British National Corpus) are:
British Academic Written English concordancer;
British Academic Written English Corpus

2. Make your own concordance! Laurence Antony at Waseda  University made Antconc, a free software for making your own concordance.

3. Google can be a simple concordancer too: