Perspective:
http://blog.nathanbransford.com/2015/02/4-tips-for-handling-multiple.html
Character:
http://jodyhedlund.blogspot.com/2014/10/planting-minor-characters-with-purpose.html
http://www.writersonthemove.com/2014/09/bring-your-characters-to-life-with.html
Detail:
http://dailypost.wordpress.com/2014/09/24/descriptive-writing/
http://www.copyblogger.com/damn-good-sentences/
http://www.writersonthemove.com/2013/11/use-seven-senses-to-spark-your-writing.html
Plot and story arc:
http://storyfix.com/the-irrefutable-algebra-of-story
http://storyfix.com/easy-approach-story-building-bedtime-story-model
http://blog.janicehardy.com/2013/10/plotting-with-save-cat-beat-sheet.html
http://blog.janicehardy.com/2013/10/plotting-with-heros-journey.html
http://blog.janicehardy.com/2013/10/how-to-plot-with-three-act-structure.html
http://storyfix.com/value-pantsing
Polish:
http://storyfix.com/fiction-writers-definition-criteria-concept