You cannot invest and be sure you won't lose them. ALL investments carry at least some degree of risk. At the same time, savings are unfortunately a waste of time. You put $300 euros in a savings account in 10 years it will be worthless due to inflation. Stocks are probably not for you, since you only have 300 euros and most stock brokers insist on a much higher minimum to open an account.

I have investments in bitcoin but that's a bit technical unless you understand it I'd advise against it unless you know someone who is already into it. Honestly, for 300 euros, I'd buy silver. You can buy actual bars of silver online and they ship them to your door next day. 300 euros that's about a pound (half a kilo) of silver at today's prices. Buy some silver bars, and stick them somewhere safe. I think silver is going to do well over the next 5 years, and nothing beats physical possession.

300 is a waste of time - fees and transaction costs will eat up more than any expected ROI on something that small.

Stick it in your pillow and save it for a rainyday fund; ask this question again when the amount you are looking to invest with is in the high 4 digits preferrably 5.

Invest it in a college education :)

Hello everyone i'm 19 years old and i want to invest my money instead of just spending them without purpose what is the best solution in investing money but to be sure i won't lost them ?

Thanks :)