Free classified ads are a great source of advertising. You can place ads everyday. Don't spam the ad sites. They will ban you. Read their terms of service to see how often you can post.
TIP:If an advertising site says your ad lasts 30 days, that doesn't mean you have to wait that long to post again. Look at the other ads and see how long they've been on the board. If they move quickly, you can probably post more often.
Just because you can place free ads doesn't mean you shouldn't try a few paid classified ads. These get more attention and can be very successful. Be sure you track them to see if you are getting clicks. If you are getting clicks and not sales, the problem might be with your sales copy. If you are not getting clicks, the problem might be with your ad copy or the site on which you are advertising. The best ad tracking system I have found is Hits Connect
TIP: Sometimes tracker links are very long. If you have long urls and want to shorten them, Tiny Url is a great place to do this! You can do that here:
Remember, when placing a classified ad you are not trying to make the sale in the ad. You are trying to draw a click to your sales page where you then try to make the sale. Don't make outrageous income claims to draw visitors. This will turn them off and you will waste your time. Just give them a good reason to click your ad and visit your site.
There are ways to make placing a classified ad much easier. Everyone needs this tool that makes ad placement 'a breeze'. It is called AD WIZARD. It is highly recommended that you check their free trial. If you decide later to purchase it, it is only $10 well spent.
AD WIZARD comes pre-loaded with a lot of free ad sites. Just program in the variables: ad title, the ad, your URL to your site, etc. Then you go to the ad site, click a button and it places your ad for you. Again, it's free to try so Go Here to get it now.
TIP:Get yourself a good business email account for placing ads because you may get several hundred emails per day! There are a lot of free email accounts availble to you. My favorite is Gmail. If you can get a Gmail account you can sort all of you mail into categories so you don't have to wade through a ton of mail to get to your most important email. If you don't have Gmail, find a friend that does and ask them to invite you to open an account (that's the only way to get one at the time of this writing.
Here are some good sites to get you started:
AdTrack Classifieds
NetBizWorkshop Classifieds
You can find a decent list of classified ad sites Here or do an Internet search for them.