Well I don't know about beg, I've been wanting to teach Meeko that myself. I just can't figure out how to do. I tried holding treats just above him but he isn't going up.
I can help you with shake tho, Meeko is a pro at it. Just show your baby a treat and then close your hand over it. It may take a lil bit, but your dog will eventually start to paw at your hand to try to get the treat. As soon as she starts pawing, mark her command. Wait untill shes pawing your hand fast, every single time and then start adding your word. It only took Meeko about 20 minutes until I added the word.
You didn't ask about this trick, but I thought i'd add it anyway. Here's a thread I started a few weeks ago and someone asked how to teach Bang Bang (play dead) and I explained it. I hope the link words.
http://www.yorkietalk.com/forums/sho...d.php?t=123556
Good luck training!!!