Good introduction to web hacking: https://www.hacksplaining.com/
Learn Python http://www.pythonchallenge.com/
Current events blog: http://arstechnica.com/security/
Good range of problem solving challenges: http://www.hacker.org/
Practice from easy to impossible: https://pentesterlab.com/exercises
Vulnerable by design VMs: https://www.vulnhub.com/
Programming challenges: https://www.codewars.com (join clan “Void Star”!)
Get paid for finding public exploits: https://hackerone.com/hacktivity/popular
Problem challenge site: http://overthewire.org/wargames/
Former CTF questions archive: http://captf.com/practice-ctf/
When you want more: http://www.amanhardikar.com/mindmaps/Practice.html