I use a simple method but I don't know if is 100percent save. Someone should correct me if is not.
I use coinbase payment.
Coinbase commerce => create checkout => I put all my product information e.g description, price => I upload my product image => they generate code for me => I use it to embed in my website
However, if you work with one client at a time, you really don't need third-party payment services. You could just purchase a hardware wallet, connect it with Electrum, and send each client a new address to pay to. The hardware wallet safely stores the private keys for you, and you use Electrum's addresses tab to copy addresses were you will receive your payments.
This is what I was doing, but I do not use hardware wallet or connect it to Electrum. This method is good and secure if you want only you to control everything about your business payment.
As a crypto investor, I am also interested in generating wealth outside of FIAT currencies.
If you are crypto investor you are generating wealth outside of FIAT currencies already. Which other wealth you want to create.
Also if what people reply you above have help you. You can come back and comment and they will know that their comments help. But if you are finding difficult you can come back and comment and more help can come don't be silence.