I am really new to the stock market. About a year ago I went in and put some starting capital for my kids and put it into equity funds (is that what it is called in English?). Then I didn't check or follow up for several months. So then I finally checked and was like, wtf, I had no idea the stock market was going bananas. I thought, with absolutely no information, that the money would basically be zero given how society was doing. So now I've been using my spare money to invest. It's not a lot. So I am wondering if you have any tips for a newbie?
My investments are mostly made domestically (Sweden) because a friend told me to avoid foreign markets due to double taxation. Then like a week ago another friend told me that it wouldn't be a problem. So I sold off what I could and invested into companies that I like. Sonos, Blizzard, Nvidia, Garmin and for symbolic value I purchased ten Juventus stocks.

Right now all my money is tied but I am hoping to be able to invest more in the future.