I have always liked the 5 foot rule. If someone is within five feet of you they will have my card in their hand. I am a little shy about doing this at times but they have the choice of throwing it away. I don't pressure anyone but just use a simple comment like "if you need an electrician don't be afraid to call me." Works great when your standing in line waiting around doing nothing. If they are interested you will know right away and get some great face time. Even if it leads to absolutely nothing it is great practice on your people skills for the price of a business card. Plus it helps pass the time waiting in a line.