If you are aware of a girl looking at you from across a room, and holding your gaze when you make eye contact for a few seconds longer than is necessary, this is a strong indication that she's interested in you. Watch out for her breaking eye contact to glance down at your mouth during conversation, suggests sex expert Tracey Cox in the article, "Decode His Body Language" in "Cosmopolitan." This is her subtle way of letting you know she likes the idea of kissing you, explains Cox.

A girl who is imitating your body language is doing some subtle flirting, reveals Cox. You may become aware that she is mirroring your movements, such as crossing her leg when you cross yours. Another example of flirtatious body language is moving into your personal space, which flirtation consultant Judy Dutton defines as the 18 inches immediately surrounding your body. She may inch closer to you to whisper into your ear, then not move away again, says Dutton in "How the Science of Sex Can Make You a Better Lover." A girl may bring her hands up to her face or play with her hair when she's flirting, says international dating website eHarmony in the article "5 Body Language Signals and What They Mean."

A more obvious sign of flirting is making actual physical contact, but it may still be done in a subtle way. Your date may unnecessarily brush her arm against yours as she walks past you, let her hand lie next to yours on the table and graze her finger against yours, or lightly touch your elbow during conversation. These gentle touches can be electrifying, says psychologist Dennis Sugrue in the article, "The New Rules of Flirting," from "Cosmopolitan."

A girl who is flirting with you will only have eyes for you. She won't care what's going on elsewhere, and will appear interested in getting to know you better. If she's paying you compliments, laughing at your jokes, whether they are funny or not, smiling frequently and listening intently to what you are saying, you can rest assured that she's keen.