

Learn to shift based off the sound of the engine, dont stare at the tachometer.
Do not do this.
Every engine has a different redline. The redline is based mostly on piston mass, which doesn’t necessarily correlate directly to engine displacement, given that it’s common to have 4, 6, or 8 cylinders in a car. If you’re shifting primarily based on engine sound, you can be shifting too low in one car, and then too high in another. The tachometer is a much more reliable way of learning where you should shift in any given vehicle.
Also, constantly running your car in the maximum power band–which tends to be close to the redline–probably isn’t great for it.
Honestly, my advice, unpopular as it might be, is that unless you plan on riding a motorcycle you should probably get an automatic transmission car instead of learning on a manual transmission. Manual transmissions–in the US, anyways–are largely relegated to performance vehicles where people want them. But the hard truth is that automatic transmissions do a better job at driving efficiently and keeping the engine at a safe and ideal load than any driver with a manual. And it’s a lot less hassle for most of the driving that people tend to actually do. For instance, it’s uncommon to have a cruise control on a manual transmission car, which makes long drives more tiring, and stop-and-go traffic puts less wear on an automatic transmission.
If you plan on riding a motorcycle though, you must learn to use a clutch, because all non-electric motorcycles use a clutch (usually a wet clutch, but Ducati uses a dry clutch); manual transmissions are lighter and more compact, and weight matters a lot on a motorcycle.
I say this as someone that learned to drive on manual transmissions, and exclusively had cars with manual transmissions up through about 2022.