It's a combination of many things. Research, finding spots that haven't been searched before, will greatly improve your odds. I'm no expert, I have only been detecting about 4-5 months, and it took me a while to find the shiny stuff.
My best advice if you want to find a silver coin sooner. If you can make nice clean plugs, and the soil is nice and damp, take a drive this weekend. Look for older houses having garage sales. When you find one, look around for a minute, then speak to the owner. Tell them you do metal detecting, and they have a very nice house-property. Ask them if they have ever had someone detect it, and that if it's old, there's probably some interesting stuff under the grass. Sometimes they think its the coolest thing ever, and sometimes they just say no. Don't get discouraged. It's between you and them what happens to what you find though.
Old city houses have old coins. Concentrate along sidewalks, front and back doors, driveways, etc.
I hope this works for you. I can't imagine what it'd be like not finding a single silver for 2 years. Even if you're not too sociable like I am most of the time (anxiety), garage sales are a great ice breaker, especially if the house is owned by a sweet old lady...
Good luck, now go find some silver!
-Ron