How to tell a cat you're a friend

Check out the Caring for Strays and Ferals forum for tons of ideas and suggestions!

http://www.thecatsite.com/forums/forumdisplay.php?f=9

Was this near your house? If so, just frequently go out and call to her. Cats are extremely astute and I bet she knows you are a nice cat lover and will return to that same area again, if she was actually lost. You could put some food out, but might attract other strays then as well. And that is a whole other ball of wax, so to speak. Sending vibes for the little Siamese and hoping she just went back home.

I would start putting food out and checking on it often. If you believe that you may run into her again you may want to carry a can of cat food with you and set it down when she's nearby. Do it as non-threatening as possible. Hunch down and make slow motions as not to scare her. Then move away from the food so that she can come and eat. Remain hunched down or sit as this makes you less threatening.
Never chase the cat. You won't catch her and will just scare her. I normally just sit down on the ground, call the cat with a kind voice and tap my fingernails on the ground to get her attention. Even with friendly social cats it will sometimes take some time to build a rapport with them. A lot of patience and time is required. You may have to do a lot of just sitting there and watching the cat eat. You can try to lure her with some smelly food. If she won't come up to you throw it on the ground a few feet in front of you then just stay there. This lets her know that she can come near you without anything bad happening. You basically have to gain her trust. I've never tried this myself but I think it may work to get the cat to come near if you throw a pile of catnip on the ground. It's worth a shot.

If you have gotten her to eat near you once but you couldn't catch her keep coming back every day at the same time to give her food. In some odd way cats can tell time. Continue to get her used to you and as soon as she comes up to you and you feel that you can pick her up without her being scared away first you can pick her up, grab her by the scruff so she can't squirm out of your grip and then put her in your car, take her inside or put her in a carrier. A big carrier is easiest. If your goal is to catch her I'd grab her first chance you get since you never know if you will get a second one.

Good luck

It does take a TON of patience....but she will probably come around. Since she seemed interested in your "meow" that sounds like a good sign! If you put food out every day at the same time, and just kind of watch her, she will start to understand that seeing you means good stuff for her

As the other posters mentioned, very calm, slow non-threatening movements are best. The most important thing I've noticed is to not approach the kitty (and definitely don't chase her!) - let her approach you. It will take some time. Once she has started approaching you on your own, start gradually holding out your hand a little (palm up). Chances are she will eventually brush up against your hand and maybe allow you to pet her. At least, that's how I ended up making friends with my beautiful calico kitty Talley! Her former "family" had abandoned her, and she was very wary of people. She would bolt instantly whenever she saw me. It took lots of days of just putting out food before & after work, and watching her/calling to her... but she is now an indoor kitty and my best friend, follows me around the house and sits on my lap for hours

Good luck with the kitty!

Start putting food, dry, wet, all sorts of food near the area where you saw her