Here are links to articles with writing tips or common writing errors authors make. Weeding out errors will tighten your prose and make your story easier to read.
Most Common Writing Mistakes, Pt. 58 — an excellent post on writing description, by K. M. Weiland
Ten Reasons Why I’ll Quickly Reject Your Story by David Farland
Natural Reader — A free version is offered for download. This text-to-speech software allows you to listen to someone else read your work, helping you to catch errors you might overlook when reading it yourself.
The articles at these links address the specifics of writing in various genres:
The Logline as both a sales and writing tool — Excellent article on writing loglines. The logline should be written before the story. It’ll help you prove your concept.