How do cookies affect your earnings? The sites you visit place a tracking cookie on your computer. You NEEd to allow these cookies to be placed in order to be credited. However, a huge tip I learned was that you also need to remove these cookies once you're done.
As you know, many sites have multiple offers. Take a look at this example:
Say you go to OFFER A on COMPANY1's website. COMPANY1 will place a tracking cookie to register that you were there. Move down to your list of offers, and you'll come across OFFER X which also happens to be from COMPANY1. If that cookie is still there, COMPANY1 will just say "Oh, she's already been here." and you won't be credited. But, if you've already deleted that tracking cookie, COMPANY1 will not see an already placed tracking cookie, and you will be seen as a new visitor and credited for the work.