Do you have any extra income besides your main job?
What can you recommend as an additional income?

And I've been thinking about investing in cryptocurrency and increasing my money for half a year now.
I am still very inexperienced and have studied very little about the cryptocurrency market and mining in general.
But my best friend advised me of one proven mining cryptocurrency pool for investing in cryptocurrency.
I'm thinking about investing not a big amount, but for a long time, and then look at the circumstances.
I will be very glad if you advise me on what I need to learn about cryptocurrency, so as not to lose money?

The most important thing for a beginner is to learn the most basic information about cryptocurrency, how it works, how to follow the charts, how to withdraw later, and so on.