Leliana is bisexual so you can romance her as either a male or a female Warden. The unique gifts (Andraste’s Grace flower and the Cute Nug) seemed to boost approval much more on the console than they do on the PC. This is for the PC version, but it should get you close on console, as well. The approval rates vary slightly from the PC.
Note: I had an opportunity to play on the PS3 recently. Obviously this post contains information about Leliana, so if you don’t want spoilers, please do not read any more. There are posts for other characters as well.
