Websites and tools to help you write better

US government plain language guidelines.

Plain English Campaign (started in 1979) 

Dialogue Punctuation guidelines

FREE Screenwriting Tips, Advice, & Downloads

Sites offering royalty-free stock photos for commercial use

stocksnap.io
unsplash.com
splitshire.com
jaymantri.com
gratisography.com

Some good images available at the above sites, but Pixabay.com remains the daddy of  royalty-free image sites by a long long way

Looking for free Stock Music, Stock Video Clips, Sound Effects & Video Templates check out mixkit.co

One of the best free online spelling and grammar checking tools
spellcheckplus.com

One of the best free online photo-editing sites
pixlr.com

To blend your own photos with imagination for free.
Photofunia.com