Lukas as to what you specifically invest in, it’s a very personal choice.
I have a very conservative portfolio, composing of bond ETFs, REITS and index ETFs. The sole purpose of this fund is to be highly passive, relatively stable income. As a result, returns aren’t as huge as they could be, but that’s the price I pay for being passive.
I have then taken a view that I should invest in what I know - websites, or “internet real estate” if you will. This is higher risk, higher returns and much more active income.
This is all personal preference up until now but as others have touched on, taxes and fees are a major concern. Almost everything you read online is about US investors, which isn’t suitable for us nomads as a “low cost index fund” that see 30% of it’s dividends taken in taxes when sent to a non-resident.
What made my journey a lot easier was thinking of myself as a resident of Singapore. I am not a resident of Singapore (I’m in Andorra), but if you read their guides on investing and the products available to you, you’ll realise that many Singaporeans invest in UK domiciled funds, which have a 0% dividend withholding tax. There are other regions as well (this is just an example)…
If you’re planning to invest in more traditional assets, I suggest checking out some Singapore money blogs and FIRE stuff. It is quite insightful.