How to Make WordPress Site Secure from Hackers?

[Alphagalaxy]

Would like to know all possible way to make my WordPress site secure from hackers.
Are there any experts who can share their tips here?

One of my co-workers shared these ones:

• Create WordPress Sites on FLATsite
• Use TLS or SSL Certificates
• Utilize DDOS Protection
• Implement a Website Back-up

Have you tried FLATsite static wordpress site generator? Is it really good solution?
So, could you share your view points on securing wordpress site from hackers?

Thanks.