Ask HN: How to get into offensive security?

I understand web application security, that means I know what the OWASP top 10 are and I know how they work. Given a 0-day I could write a script for it. I understand what people are talking about when I listen to a defcon talk or security podcast. I know what a buffer over flow is. I also understand the basics of cryptography and can write/read assembly if I absolutely have to. I know how to read/write iptable rules. I have taken part in CTFs.

1. How does one start doing bug bounties?

2. How does one start finding 0-days?

Are there any online courses that are good at teaching the above?

I don't want to find 0-days because of malicious reasons. I want to learn how to find them as articles about them seem clever. I like the exploratory nature of it.