If you would start again, how would you do it?

It seems that there are a lot of things to consider before even buying the first smart device. How would you start when you would start over?

Are there any good beginner guides that helped you?

Important points for me are

• privacy (everything should be local, no Alexa-Karens in my home)
• use of open source/free software
• a good variety of smart things I can use (I don't want to be tied Apple-like to only one company)

Is there a golden way to build a smart home with these factors in mind?