Long time lurker here, thought I would drop what I look at before signing up anywhere. After a few bad experiences I stopped trusting the big banners.
I always start with licensing: find the licence number and look it up, and whether they actually accept players from your country. Next come deposits and withdrawals: I want at least one fast e-wallet option, and there should be no weird fees on cashouts.
Bonuses are the tricky part. Wagering of 35x or 40x is normal, and live tables often do not count at all. A decent independent write-up with the current terms is worth a read here [url=https://www.tumblr.com/soldkryptohub/829748482633056256]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. Ask support one simple question first: a real human reply beats a bot loop.
That is about it. Only play with money you can afford to lose.