Those suggestions are all good ones, but I think it's really important to understand that in order to really evaluate the content of a scientific study, you need some training. I'm not trying to suggest that people without training can't educate themselves on medical matters, but it takes more than knowing the difference between a case-control vs. cohort study, you know? There are many intricacies involved in scientific research that aren't really easy to just "teach yourself." For instance, reading through a study and knowing if they used the right stats, and whether they reported the right tests of assumptions and significance to go along with them, isn't something that you're going to learn from the internet. It's just not. Knowing whether the authors adequately addressed the limitations of their sampling and design choices also requires formal training. Those are just basic things about research, and not even specific to medical research, which is pretty complex.
I totally agree that there are excellent steps people can take to decide if the source is reliable, and something they would consider reading. Getting a general feel for the results is also something that one can pick up with some practice and background learning. However, it's not accurate to suggest that one can become as fluent in research evaluation as a trained scientist, just by looking things up in a book, or on the internet. I've been learning how to conduct research as my full-time job for many years now, and I still consider my skills to be developing, and realize my own limitations in understanding research.
Contacting researchers to ask them about their studies is perfectly acceptable, too. They always provide correspondence emails on the articles, and while some researchers are really busy, many are happy to take the time to explain their results and discuss implications. If you have questions, don't be shy!
