Blogs can be good information sources, but some are more credible than others.
Read blogs carefully to make sure they are not trying to sell you products. Also, pay attention to where they come from / who writes them, etc. If you know the names of prominent researchers in your field, it may be worth it to see if they blog about their work.
Searching for blogs can be difficult -- because there are so many in so many different fields, it can be hard to figure out which ones are the best.
Google searches (e.g., biology blog) can be helpful. In addition, some magazines and journals keep lists of recommended blogs that may be useful. Some blogs also link to other blogs on the same topic.