Please find out, BEFORE you reach the lounge, which cards you have complimentary access available.

I am all for utilising multiple credit cards for lounge access - I have 5 myself. However, for god's fucking sake, find out which one you have complimentary access available on before standing in the lounge entry lines. Not kidding, at T1 Delhi, one guy pulled out his stack of 15 or so cards and asked the attendant to check all one by one. This went on for 15 minutes -_-