Following are some good resources -
Burpsuite Basics: https://www.youtube.com/watch?v=m3LdoqYDyuI&list=PLkW9FMxqUvybgx3pI9x9HyU-_HcJJFWQY
Hackerone reports - https://github.com/reddelexc/hackerone-reports ---Must read
Vulnerability Details (How to find,tools to use,references- this is most informative github repo)- https://github.com/swisskyrepo/PayloadsAllTheThings ---Must read
Network Penetration testing - https://www.youtube.com/playlist?list=PLLKT__MCUeiwBa7d7F_vN1GUwz_2TmVQj
Web Application Penetration Testing - https://www.youtube.com/playlist?list=PLLKT__MCUeixCoi2jtP2Jj8nZzM4MOzBL
Youtube Channels: Hackersera, Hackersploit,
Some more resources -
https://reconshell.com/bug-bounty-resources/ https://gowthams.gitbook.io/bughunter-handbook/checklists
How to hunt - https://github.com/KathanP19/HowToHunt
https://github.com/1ndianl33t/Bugbounty-Resources
Bug Bounty Roadmap - https://github.com/1ndianl33t/Bug-Bounty-Roadmaps
Bug Bounty Dorks to find programs - https://github.com/sushiwushi/bug-bounty-dorks/blob/master/dorks.txt
Payload Lists - https://github.com/danielmiessler/SecLists/
Also, particularly for bug bounty, you can search Proof of concept Videos on youtube for a particular vulnerability. Some people upload them on youtube after the bug is fixed.
PS: Nothing is sponsered.