Below are a small selection of resources that any writer (but especially a scientific writer) might find useful in the course of their work.
Glass Phoenix Studios has no affiliation with any of the linked sites.
Reader Expectations
George Gopen is notable for dissecting (technical) English writing not from the perspective of grammar, syntax, and convention, but in terms of how a reader interacts with the substance and structure of the text: where they expect to find connections and key messages, and what textual mishaps cause their understanding to be delayed or outright derailed.
The articles at the above link are all readily available and provide a good grounding in the interplay between reader, text, and writer.
Purdue Online Writing Lab
The Purdue OWL is a quite thorough resource on all aspects of writing from conception to mechanics, including accessible information on using the major citation styles.