I agree with Snooks; getting the dog to touch your hand with their paw of their own will is much more natural to them, rather than you snatching her paw.
Targetting is simply teaching the dog to touch objects(or you) with paw, nose, chin... This is beneficial in many advanced tricks. Use your dog's natural curiosity to teach this trick. For instance, to nose-touch your hand, use your thumb to hold a treat in your open palm with it facing the dog. The dog of course will go to grab the treat. Click and allow the dog to take it---but only after the click. Continue this several times, then just hold your open palm facing the dog(no treat) and say, "Touch!" Give her a second or two to process it and try to figure it out. If she doesn't, try the treat again a couple times and then give her another opportunity to do it without the treat in hand. Jackpot when she gets it right. You can advance this to touching objects later.
So let's say you want to teach object discrimination(knowing objects by name). Just as you held a treat on your hand, place her in a sit and place a treat on a rope(or whatever). She needs to be advanced enough that she knows not to break the sit to get the treat. You may point to the treat or say, "Okay(this is the RELEASE), touch the rope." When she takes the treat, click and reward her again(along with the treat she took from the rope).
Let's say for instance you wanted to teach your dog to pick up a ball. You sit the ball down, and the dog looks at it. That's interest. Click and reward! After a little while, she decides to try harder, and touches her nose to it. Again, click and reward! Then she decides to mouth it. You guessed it---click and reward. And so on...the same is true with paw targetting. Reward for the desired behavior.
Targetting usually involves letting the dog think for themselves and figure out what gets them the tasty treat(pawing or nosing). With other tricks, you're usually luring...but here, the dog has to think on her own.
So, if she's not getting frustrated and pawing your hand on her own in an attempt to get the treat, try targetting. Get a target stick or something and teach her to place her paw on it. Once she's got it, hold the target on your hand. Eventually you can remove the target and she will understand that your hand is also a target. When she gets it right, jackpot.
Remember to reward for the slightest attempt(barely raising the paw, rather than just waiting for the desired "shake"--chances are she may not "get it" yet, and if you don't reward her for trying then she'll get burnt out and give up).
Hope this helps! Good luck!