What are some good books or blogs to improve my copywriting skills?

I highly recommend Carol Tice's http://www.makealivingwriting.com/ 

Highly recommended:

=> How to Write a Good Advertisement by Victor Schwab

=> Tested Advertising Methods by John Caples

=> Scientific Advertising by Claude Hopkins

=> The Copywriter's Handbook by Robert W. Bly

=> Breakthrough Advertising by Eugene Schwartz

=> Positioning: The Battle for Your Mind by Al Ries and Jack Trout

=> The Boron Letters by Gary C. Halbert

=> https://copyhackers.com/

=> http://www.awaionline.com/

=> http://www.infomarketingblog.com/

=> http://swiped.co/

=> http://www.bly.com/reports/

=> http://copywritersroundtable.com/

=> http://www.earlytorise.com/

John benson Letters 

The adweek Copy writing By the great Joseph sugar man The War of Art 

I Like Kopywriting Blog as it provides useful information 

to increase more vocabulary and  fashion oriented words