If a casino has a good reputation in the industry, they also work a lot with the security around your personal information and the account information you have provided when you register. They do not want to put hooks on themselves by being careless, then they will not be long-lived online.
Most casinos have a proper and updated firewall that keeps the information you have provided secure, it should only be accessible by staff who need it in their work and all information send to the site, ie your personal information and any transactions, is encrypted via SSL (Secure Sockets Layer) or via TLS (Transport Layer Security). These services are always active, 24 hours a day, 7 days a week.
Some tips to take advantage of are to read carefully about the casino before you start playing. What reviews have it received from other players, what experience did they have and did they get their possible winnings paid out within a reasonable time.
What security does the casino work with, what certificates and licenses do they have. There should be such information with links on the casino’s page so you can go in and read more about them.
Make sure that it is easy to contact support both by phone and email and that there is a large variety of means of payment. Even the casinos that do work hard with security for their own part and sometimes they may need more information from you before they pay out their winnings, they also do not want to be exposed to fraud and can request extra proof that you are just you.
If you are at least unsure of the casino, do not play there, there are plenty of casinos that meet all these requirements and are serious in the market.