usually i try to understand first what is the offer of luxury hotel/resort where i want to go.... i usually look to kiwi collection to get a few good names... then slh or leading hotels or fivestaralliance...
once i'm clear about the alternatives i check details about the ones that seems good for me...
i read reviews on tripadvisor, hotel website, compare pricing on hotel website and other (expedia, booking.com, kiwi, etc...).
finally i ask details in thread about the ones i really want to be sure...
this process happens only when it's a relevant vacation; otherwise if it is just one night in hong kong or london, for example, i just pick one conveniently locate about the ones that i know are going to be good (fs, mandarin, ritz, etc...)

The_Daddy