Been reading this board for a while, so here is what I look at before signing up anywhere. After a few bad experiences I stopped going by ads alone.
First thing is the licence: find the licence number and look it up, and whether they actually accept players from your country. After that I look at banking: I want at least one fast e-wallet option, and there should be no weird fees on cashouts.
Never judge a site by the bonus alone. Wagering of 35x or 40x is normal, and the bonus usually expires in a week or two. A decent independent write-up with the current terms can be found here <a>meer informatie</a> before you deposit anything.
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.
Anyway, that is my routine. Set a budget and stick to it.