It's important to carefully organize your research findings, to make writing and citing easier. Bookmarking an online resource might seem like the easiest way to keep track of it -- but it won't always work, as many databases create temporary urls (session IDs) that will expire. When you return to the resource at a later time you may find that you can no longer access the article.
Here are librarians' favorite ways to keep articles together:
Some individual databases also allow you to create free personal accounts on their sites. These accounts will allow you to save articles to return to later. ProQuest and EBSCO are two examples, but there are others. Look for a "sign in" or "register" link when you're searching.