Don’t do it.
With a normal casino, you have to get up and physically go there, if you gamble online you’ll find yourself gambling all the time and losing money on a much more consistent basis. You’ll gamble at home in bed, at work, in traffic, etc. (You can gauge this by paying attention to how you get in an actual casino and then multiplying it by 24/7 access)
You’ll also run into a lot of shady/scam casinos online, my example is CLUB PLAYER CASINO.
Club player has these great deposit bonuses, but what they did to me was they added all of the bonuses up that I received from my deposits over a few months, and then when I won and tried to cash out, they took a month to process it, even with me contacting customer service daily, and then denied it because my $800 withdrawal was actually worth $16 after they deducted all of my bonuses I’d ever received, and their minimum withdrawal is $100.
The bad part is, there’s probably worse out there (I assume a lot of the posts in this subreddit and r/onlinegambling asking players what they like in an online casino are from people trying to start their own scam casinos)
Even some of the more reputable casinos have some annoying ass practices, for example betonline has daily/weekly tournaments where the prize money is actually a promo balance with a 50x rollover, meaning that if you win the $3000 first prize, you have to make bets totalling $150k in order to cash out.
But if you’re dead set on gambling online, then make sure you READ REVIEWS before using a site. Also make sure you read ALL OF THE FINE PRINT if there’s any bonuses or prize money not requiring a purchase. Also, at least skim the website’s TERMS & CONDITIONS to make sure there’s not too much fuckery.
And if the website has it, make sure you set limits on how much you can deposit or lose. I know Chumba Casino has them. They also have a 5 day waiting period if you decide to remove or change your limits, so you don’t lose and then immediately email them so you can go chase your losses.
Another thing you want to do is cash out frequently. If you’ve deposited $100 and win $500 but you can’t stop yourself from playing, withdraw that initial $100 and try to avoid going and cancelling that withdrawal after you lose the other $400.
That’s pretty much all I can personally think of, but anyone else with experience please feel free to add more.