This is not legal advice, but based on my research.
1. Don't buy a house in Spain, rent. Same with a car, rent instead of owning assets.
2. If you want to stay in Spain over 183 days, you need to establish tax residence somewhere else too, and form stronger ties. For example, in Barbadas, UAE, or elsewhere, set up a tax residence, which you can do while living there for much less than 6 months that most countries require. Also buy an apt and car there, it can be very cheap, like a used car and a hole in the wall. Join gyms, memberships, etc to have something to show. Ideally, it's a country with a doule taxation treaty with Spain.
3. If Spain ever comes after you for taxes, show you're a tax resident elsewhere, with much stronger ties, and they would probably lose based on that.
4. Enter the EU from another country and then go to Spain. That way, it will be harder for them to check the number of days you're in Spain. If you also don't have bank accounts in Spain, there's little to nothing that would even flag them to look into you.
5. Never get a NIE. If you do want a bank account, you can open a foreigner account at BBVA by paying around 200 euros a quarter for their health insurance, which is also useful in Spain.