Long time lurker here, so here is my short checklist for choosing a casino site. After getting burned once or twice I learned to read the small print first.
Licence comes first for me: find the licence number and look it up, and if your country is on the allowed list. Next come deposits and withdrawals: card, e-wallets and bank transfer should all be there, and there should be no weird fees on cashouts.
Never judge a site by the bonus alone. Anything above 40x rollover is a red flag for me, and live tables often do not count at all. A good recent review that covers all of this is here play at Craybet and it saved me some time.
I play almost only on my phone, and if there is an app I make sure it comes from the official page. Test the live chat before depositing: slow or scripted answers usually mean trouble later.
That is about it. Treat it as entertainment, not income.