How can you apply critically thinking skills when evaluating the media?

The reason to apply critical thinking is that if you don't, you will wind up believing things that are not true, and could be fooled into buying worthless products, and so forth. The method of critical thinking basically is to use everything you know, and try to see how a given statement fits in with your other knowledge. However, if you don't know very much, you may need to get an education first. Also read "The Demon Haunted World" by Carl Sagan. That book is very helpful.