One great way to improve your screenwriting is by reading scripts. Here are several Oscar Nominated scripts for you to check out free online!
Trumbo:
http://assets.bleeckerstreetmedia.com.s3.amazonaws.com/fa4fc708-cc5a-4eae-866a-5eafa4e39104/full.pdf
Bridge of Spies:
http://www.dreamworkspicturesawards.com/downloads/BOS_Script.pdf
The Hateful Eight:
http://twcguilds.com/wp-content/uploads/2015/12/H8_SCRIPT_CleanedUp_Final1.pdf
The Big Short
http://www.paramountguilds.com/pdf/the-big-short.pdf
Straight Outta Compton:
http://www.universalpicturesawards.com/site-content/uploads/2015/08/Straight-Outta-Compton-Screenplay.pdf
Let me know you find this helpful!
Cheers