My general advice on internet casinos (having played in them for 10 years plus):
1) If you've not heard of it, don't play
2) If it takes Amex / Diners, don't play (typically normal online casinos don't take these particular cards)
3) If it accepts USA players but is not licensed in a US friendly location (e.g. Atlantic City etc), be careful where you play (some are ok, some are not)
4) If a bonus seems too good to be true, it probably is. Eg. If you get offered 5000% bonus, with small playthrough requirements (e.g. x5) then you may not ever get paid.
I'm sure others in these forums can offer advice too.