You have to decide where to look, how to recognize credible sources, and how to cross-check your information.
Learning how to evaluate effectively is a skill you need both for your course papers and for your life.
While some of them are written by real experts and can be great sources for some topics, many are strongly opinionated and can lack the professionalism expected in a scholarly source.
In some papers on contemporary or Internet-related topics, it might be appropriate to use a blog though, especially now that many famous politicians and media personalities are blogging.
Regardless of what type of sources you use, they must be credible.
In other words, your sources must be reliable, accurate, and trustworthy.
Here's how you can use Wikipedia for your research: Wikipedia can be great for your first research on a topic.
It has such a broad subject matter available and it can connect you to further research on the subject.
Also, blogs can make money by selling ad space on their sites, so beware of excessive ads.
Beware that there is no bar for entry and no quality control for blogs.