Long time lurker here, but I figured I would share how I pick an online casino these days. After getting burned once or twice I learned to read the small print first.
Licence comes first for me: see which authority is listed in the footer, and if your country is on the allowed list. After that I look at banking: I want at least one fast e-wallet option, and the withdrawal limits need to be written clearly.
Bonuses are the tricky part. Anything above 40x rollover is a red flag for me, and some games count less towards it. A decent independent write-up with the current terms is here Revery Play so you know what you are signing up for.
I play almost only on my phone, and a good site loads fast and does not log you out every five minutes. Support matters too: if they answer in a couple of minutes that is a good sign.
That is about it. Treat it as entertainment, not income.