Some scammers can get quite creative so it's impossible to list all the scams in existence. But all scams have one thing in common - they always require you to send your money first and in return get some profit. When you see an opportunity like that, you should get very-very suspicious and very carefully examine it. There's very little legitimate opportunities that work like that, for example casino bankroll investment or yield farming, but even these things could be ran by scammers.
The scams are not always invest $10 and get $50 in return. They could be buy this product for $10 and sell this product for 2x the value. Scams are easy to spot most of the time because they do not make sense. If someone could convert your money into double the amount they would do that without your money and the same goes for selling products which can make money on your investment they would be doing it themselves.