I wish I had Known:

Hindsight and life experience have revealed an amazing concept to me: Experience comes from everywhere and every opportunity that we participate in. The ability to learn on your own is invaluable and should really be developed throughout life. The experience gained through serious hobby efforts and volunteering can be just as valuable as the experience gained at a corporate job. Volunteering often provides stretch opportunities to branch into diverse new fields and stretch our abilities and perspectives. One of the most important skills I have developed as a design engineer is being able to pick up a related, but new topic and learn it well enough to design something to meet a need. The difference between a hobby project and a corporate project is the level of polish, testing and documentation. The difference between a volunteer project and a corporate project could easily be only a paycheck depending on the project.

Overall complexity can be difficult to manage. The most important thing when dealing with complexity is to break it down into smaller, more manageable pieces. Start by getting small building blocks functional and work up to the full design.

Grammar IS important to learn for effective communication with a wide audience. Developing something technically amazing isn’t much use if you can’t write an appropriate and effective description of the solution. Yes, there are people for this, but you probably will not be able to afford to hire those people the first time and your friends and family are not likely to understand what you are trying to communicate (see the cycle?). And yes, I am still terrible at grammar.

Understand the deviations of a real world opamp from an ideal opamp:

input impedance < infinity

output impedance > 0

finite gain

finite frequency response

finite voltage rails and headroom

In the open world: higher voltage = lower current, this is the basis for AC transformers...

but when you transfer into the world of Integrated Digital Circuits

Power = Capacitance*Frequency*Voltage^2

Opamps used in feedback or in circuits like bandgaps or gain boosting can be simple single ended and choose pmos or nmos input stages based entirely on needed input common mode range. They can be high DC gain low bandwidth which is much easier to design.

When designing differential opamps, start with a good bias and common mode feedback circuit and gain will come.

The concept examples right out of text books will work if you understand the underlying transistor concepts

Had paid attention to the device parameter test benches and played with spice tools to understand the concepts better

That device physics are important to be able to rationalize and think around fundamental underlying problems

To pay attention to units... they allow you to check your work

To take the time and read the text books, and that it's ok if a single page takes hours to understand.

Find ways to make math visible

So often it REALLY is that simple.

It's entirely easy to make things on a breadboard work

Current isn't all that difficult to measure on the bench, you just have to break out the node somewhere, like the power supply connection.

Gain = output/input

The gain of an amp is mostly independent of its power driving ability

Output impedance of bias circuits is crucial and also as simple as cascoding