What website and security measure is the best way to start investing in bitcoin?

I’m from AU and basically new to investing personally in bitcoin and I know it’s a good way to leapfrog towards financial freedom but don’t know how to start. There are so many sites, apps and stuff to start putting your money into and then making sure it’s a legit and safe service that I don’t know which one to go for. And then after putting your money into it I have heard it’s not good to keep it on their site because situations like FTX can happen where all your money really isn’t yours anymore. I’ve heard of kraken exchange, anyone have their opinion on this? I want to make sure I put my money into something and then secure it someway. I’ve heard you can do this with owning your private keys and stuff. So how should I go about all this? Also I didn’t state this earlier but I’ve actually in the past given money to someone to invest in crypto since I thought they knew better than me and it was too complicated for me to start learning about investing into crypto (never really tried to learn it but am willing to start learning it myself now so that if I fail to secure my coins then it’s on me and not someone else). The site it was used on was FTX and so I lost it all I think. It was $50k+. So I really want to make sure this time I don’t make that mistake again.