Use a fountain pen. You can't press too hard: it bends and breaks the nib.
Disposable ones are good enough now, e.g. the Pilot V-Pen.
https://cultpens.com/products/pilot-vpen-v4-disposable-fount...
Fountain pens are nice too since you don't need any pressure.
My writing looks a lot better if I just force myself to slow down and be deliberate, but honestly it's a constant battle. I'd definitely benefit from practicing penmanship on it's own.
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I've had many writing classes in school and different holders for the pen etc but I never managed to improve at all. Writing is just not for everyone.