There will always be people who are successful at making money online. However, most of the "work at home" or "work online" ads, emails, and other sites you come across will not replace a normal salary. Some don't even pay you cash but instead give you credits to redeem for prizes. Others are even worse and make you pay them.
My best advice is to find a legitimate company that offers remote positions. I worked for Intuit for several years, and they have several divisions that utilize the at-home worker. They are a true employer, you fill out tax documents and you get an actual paycheck. Jet Blue is another large employer that offers remote positions.
To find the legitimate opportunities, do your homework. Start by looking at the websites of local companies to see if they offer anything. Then check out job search sites for nationwide opportunities.
Remember, if it seems too good to be true, it probably is, especially on the internet.