The best abstract advice I've been given is to say "I don't know" when I don't know. No waffle, no bullshit, no trying to save face. Saves a lot of time.
For some reason, a lot of people seem to have been told to never show weakness by admitting that they don't know something.
I had a professor who gave 20% credit for answering "I don't know" for a question on your homework (plus a little extra if you explain what you do know and why you don't know), and I stole that rule for my own class. One of my students became the VP of a chip company, and told me that the "I don't know" homework rule helped him gain a lot of confidence and save the BS.
Related to this, I "recently" (as in years ago, but already as an adult) discovered a method that, at least for me, performs the same capability without needing to manipulate my testicles. However, it may only be practicable for non-circumcised penes—I don't know.
The process is the following.
After you have finished your urination, even if (you think) you have shaken and squeezed out all that was left, you pull your foreskin back even further so it is behind the glans. Then, you use your thumb and index finger to pinch the foreskin on one side and use it as a handle to stretch your penis by pulling the glans away from you VERY lightly (no pain or discomfort please!), slightly bending the penis diagonally at that point until, usually a second or two later, you start feeling the need to pee again. Then you let go and... voilà! There's a whole new stream of urine that you wouldn't even believe was there when you "finished" peeing a few seconds ago.
I don't know if this is common knowledge, as I have never searched about it or talked about it (not out of any embarrassment or anything, it's just something so trivial). This also means I don't even know if it would work on any equipment or whether it is limited to specific internal wirings or anatomical features.
I also try not to express my opinion in absolutes – I tend to tell that "I think that...", "I believe that", "as far as I know", etc. It is, in a way, a philosophical position – I am aware that I do not know about many things, that someone may be more expert in a given field than me. So, I am trying to keep an open mind, be open to discussion, and not impose my own opinion on others just because I feel that I am right.
I have been living by these principles for years and I feel good.
However, I would not advise anyone to take similar stance. It depends on the company culture, probably it differs from country to country too... Still, from my experience, it may hurt you career. In most places where I worked, that kind of behavior was perceived as a weakness.
Hell, I remember being told that I will not become a manager, because there is no place for "don't know". But it was quite toxic workplace anyway.
The lesson, in short, was "if you don't know, say you don't know." Admitting you didn't know the answers was required to "pass" the ritual. (It wasn't actually possible to fail per se)
Many of the things we did with initiates were stupid or pointless, mostly just designed to put them through the ringer. But this one has really stuck with me as a valuable lesson. If you're missing some knowledge, just say you don't know.
It's a good quality!
Examples are my boss and their boss, who instead of saying "I don't know," would sell you their plan for nuclear fusion despite knowing fusion only in the context of fine dining. Many politicians are also allergic to "I don't know," but they continue to get elected, many journalists have no clue but continue to write for major newspapers. They don't say "I don't know," they write while not knowing, but without mentioning it.
My doctor advised "milking your urethra" (same thing as OP mentioned). It's good to do it post ejaculation too.