Affiliate marketing is a great way to make money on the Internet. In any case... don't pay for what you can get free.

Do not enroll to a program that asks you to pay even $1 registration or whatever fee... don't pay to get paid.

Verify that your site will get maximum exposure, there are lots of free ways to do it:

1) Traffic exchanges.
There are 2 major traffic exchanges sites: manuals and automatic. Manuals will get you high quality traffic. You will find lots of options to get new visitors and maybe earn several dollars from referrals.

2) Forums.
You can locate and join high traffic forums that are relevant to the content of your site. These forums will usually allow you to sign your posts with your name and website address.

3) Free classified ads.
Yahoo classifieds, adlandpro.com, inetgiant.com etc...
4) Submit your site to search engines and directories like yahoo,google etc...
Never promote the affiliate site that you got directly. Get a personal web page and promote it. Give it a general name like MyAffiliatePage. This way you will be able to switch to another program and all the marketing efforts will not be gone with the wind. You can also earn from google adsense.

5) Verify that your site is SEO optimized.

6) Enroll to groups: Google groups and/or yahoo groups.

7) Create an alias to your site via v3.com.

It will help potential visitors to remember your website name.

8) Use your affiliate site to print flyers. Distribute to friends and family.