What's a good way for a newb like me to learn things basic practical analog design things like • how to decide L/W for my transistors • most common/useful analog IC subcircuits • when not to trust the sim? Is there a super short guide or webcourse or something? I read some of Razavi's book but it is not super focused on this. Also looked at some lecture notes and youtube playlists but didn't find anything great.

Design this gm constant circuit. First, try with the minimum L and W. Simulate it varying the resistor, the temperature, the voltage supply. Then multiply L and W at the same time of all transistors by a factor. Keep all the ratios constant, and later try another ratios. This is the simplest current source, and it has only five transistors and a resistor.

I recommend any text book written by Paul R. Gray.

@Luis Henrique Rodovalho Thanks for the great exercises. Would be sweet if someone made something like nandgame.com for analog but I don't think anyone has.

There is an open source online layout tool for simulation of anything at transistor level. I forgot its name. Ask @Matt Venn

Oh I'm happy with my tools I meant more for the interactive exercises

@Luke Harold Miles we have some basic lessons / exercises here: https://tinytapeout.com/siliwiz/