Ah, the classic escape route; women often use this one when they feel cornered by someone they are not interested in. It's clean, requires no preparation and leaves no room for a counterargument. But if a woman says this to you, what she really means is that she does not want to be in a relationship with you. For whatever reason, she doesn't see you as relationship material for her, so don't stick around hoping she will be ready someday. She might get into a relationship eventually, but it probably won't be with you.
2. You're always the one calling her and/or she doesn't return your phone calls
Watch out: She may be avoiding you. And if she's not avoiding you, you are not on her mind and she simply forgot. Either way, this means that she has less invested than you do and doesn't care enough to actively seek out your company.
Here's a rule of thumb: If she doesn't return your first call, call a second time, as she may be playing hard-to-get. If she doesn't return your second call, you can rightly conclude that she's not into you. (Do allow a certain amount of leeway on this point; women have been told by umpteen dating books to let the man do the pursuing. She should be calling you at least once for every three times you call her.)
3. She avoids eye contact and physical proximity
This is an obvious sign that many men overlook. If she is attracted to you, she will naturally want to be close to you and make eye contact. If she is evading your gaze, however, she may be consciously trying to avoid leading you on and having to turn down your advances later. It's a sneaky little trick, but it usually works. Take it as a sign that you're not her type. If she keeps you at arm's length at all times, she may also be protecting her personal space, so make sure you don't get too close.
4. She mentions other guys she finds attractive
No, she's probably not trying to make you jealous -- unless we are dealing with an ex-girlfriend, a situation that belongs in another category altogether. Most likely, though, you are in the "friend zone," which means that you are just like one of her girlfriends that she shares her thoughts with. Ergo, it has never even crossed her mind to date you. Not good.
5. She tries to set you up with another woman
She might do this because, like in signal No. 4, it never crossed her mind to date you. Alternatively, she might do this because she likes you as a friend but wants to make certain you don't hit on her. Either way, the message is clear: She definitely doesn't want you for herself.
6. She doesn't laugh at your jokes
If she is consistently stone-faced when you crack jokes, then you can conclude two important things. First, she doesn't find your sense of humor engaging, and second, she doesn't like you enough to bother to pretend otherwise. Here's a shocker: Whether or not she laughs at your jokes doesn't necessarily have to do with whether or not she finds them funny. Laughing is a form of flirting, and if she isn't doing it, you can be pretty sure her mind isn't on you.
7. She is always vague about making plans
If she really wants to see you, she'll make firm plans. If she doesn't want to see you or doesn't care one way or another, you can be pretty sure that she's not into you. If she is vague about making plans, it probably means that she is neutral about being in your company, or even worse, that she doesn't want to commit in case something better comes up. Ouch.
8. She regularly cancels plans with you
Let me break it to you gently: You are the fall guy, the "just in case she doesn't have anything better to do" guy. It is certainly fair to cancel plans occasionally for a legitimate reason, but if she bails consistently, ditch her, even as a friend. If she does this, it not only shows that she's not interested, but that she holds little respect for you at all. Move on, and do it quickly.
9. Her description of the perfect man sounds nothing like you
She tells you she wants a Mediterranean man who can dance salsa. You are Swedish and can only square dance. I know -- women rarely stick to what they say are the perfect traits they are looking for in a man. And indeed, she may actually end up with a square-dancing Swede, but in all likelihood, it won't be with you. Take this as a kind hint on her part that you, for whatever reason, are not her perfect man.