Mostly a reader, rarely post, so here is how I pick an online casino these days. After a few bad experiences I stopped going by ads alone.
Licence comes first for me: find the licence number and look it up, and whether they actually accept players from your country. Next come deposits and withdrawals: card, e-wallets and bank transfer should all be there, and there should be no weird fees on cashouts.
The welcome offer is where most people get caught. Read the wagering and the max bet rule, and some games count less towards it. A decent independent write-up with the current terms can be found here [url=https://www.signupforms.com/registrations/49782]Slotshopper[/url] so you know what you are signing up for.
Most of my sessions are on mobile, 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.
Hope this helps someone. Only play with money you can afford to lose.