Decent women do not need to flirt. All you need to do is look at him twice and he will ask you dance. You dance, you will feel whether or not he is interested in you and then you make up your mind. No need to get your mouth around sayings....
Tengo ganas is crude and unless you are an off-the-wall ugly person, I can see no reason for you to say that to any may.
Are things so bad in the US/Canada/Europe that you need to tell a guy " I want to get laid!" ????? Come on people!!!
Propriety and the use of your eyes will get you respect and perhaps a nice dance and then it's up to you to decide....
A woman's glance can be a red flag for the studs at the hotels,,,no kidding, and it does not have to be one of those Hedy Lamar " Come Hither" looks either. Just a look and a smile. Be cool, girl...
Old Fashioned HB
Note: If you do not know who Hedy Lamar is, do yourself a favor and google her and see her famous " look" ...