Just got my first proper luxury car, tyre care is overwhelming

Never owned anything above a regular sedan before so this is all new to me. Picked up a used German car last month and the tyres alone cost more than my old car's entire service history. I want to look after them properly but I keep hearing conflicting things about rotation intervals, pressures, and whether the fancy low profile tyres need special treatment. I found some Premium tips for luxury car tyre maintenance that covered a few things I hadn't considered like checking pressures when cold and watching for sidewall damage on low profiles, but I'd like to hear from people who actually live with these cars. How often are you rotating and balancing? And does anyone bother with nitrogen fills or is that a gimmick?