I used to gamble a lot starting from 2005. I will share some useful tips for a newbie gamblers.
1. Do not deposit anything, before your account is not fully verified. Because any bookie will accept your bet without verifying your account, but if you win and request a withdrawal, they will refuse and ask you for verification. You might not pass it for a lot of reasons, like bettors from your country are not allowed to use that bookie, or the documents provided by you are not acceptable e.t.c...
Great tip there, a huge number of people get caught out by this.
However, it should be noted that there are also a huge number of platforms that simply don't require verification. It's best to stick with these, rather than potentially deal with the KYC hassle later.
4. Avoid playing slots, because all slot games are pre-programmed to 80/20% in the bookies favor.
This is more about actually doing some background research before playing any game.
Everybody should research what the house edge is before playing any game. Anything above 5% is just a complete joke that should be avoided.
If you can't find out the information, ask customer support as they'll probably know.