My approach to personal finance and investing is intentionally very simple because the purpose is to keep myself focused on important work and not finance stuff.

There are a couple of great new investing services that I found useful.

/ Investing Services

To hold moderately liquid assets, I like to use YouHodler. You can get 12% APY on your Euros and USD by holding the equivalent crypto fiat.
To hold my more long-term crypto assets, I use Hodlnaut. For Ethereum the APY is 5.5% and for Bitcoin 6.5%.
To buy EFTs, I like to use Degiro. Very low costs per trade (~2€) and a wide variety of EFTs. I exclusively invest in NASDAQ 100.
To buy crypto, I use Binance. Very low cost per purchase (0.1%).
I get the good peace of mind with a split like 10% (cash, highly liquid) + 20% (YouHodler, moderately, liquid) + 35% (crypto, lowly liquid) + 35% (ETFs, lowly liquid). However, the proportion should be very contingent on your personal risk profile.