Silver Tips to keep you relatively safe:

1. Silver should weigh 31.1 to 31.8 grams - any heavier it probably is fake, any lighter it probably is fake.  The mint will almost never have it lighter than 31.1 as they don't want to cheat you out of silver, they also will most likely not make it heavier than 31.8 to not "give away" free silver. (You can purchase a cheap digital scale here on eBay, you just need a small one weighing grams to the 100th, i.e., 31.18).

2. Get a strong magnet, small and circular in size (can be found at any electronics store or even here on eBay). Hold your silver piece at a 90-degree angle with magnet at the top and let the magnet slide down the surface. If it falls off or slides rapidly, it's probably fake. If it sticks, it's probably fake. It should just glide down the piece almost purposely (sort of slow and controlled, but not too slow). Practice a bit and you will get the hang of it. 

3. Hold a piece of known silver on the tip of your finger and balancing it, take another piece and give it a little tap. You should hear a nice bell ringing tone.  If it clinks it probably isn't real. 

Even if you don't buy from me, feel free to contact me with any questions you have about silver - I respond quickly and am always glad to help! Also, feel free to check out my eBay store. I post unique silver pieces regularly and at competitive prices!