Always read the negative reviews. There is no product or restaurant with a perfect rating, even for the most amazing restaurants, there are a few out there that may not have the same taste as the rest of us. Be sure to read the bad reviews to get a different point of view, negative reviews can often point out things that are overlooked by the other excited reviewers. When purchasing my mattress on Amazon recently (I'm a risk taker), many negative reviews pointed out that the mattress is too firm for them, which helps me because I like a firmer mattresses and that it wouldn't be a negative for me.
Keep an open mind when reading reviews. If you've been online for more than a week, you know that personal preferences cannot be regulated. Unlike top-notched review guides, where there is a standard for ratings, online reviews are often unregulated smorgasbord of subjective personal opinions. It is important to understand that online reviews, while helpful, is not the absolute authority on the how good a certain product or service is.
Use personal preference to your advantage. The beauty of the internet is that you can find someone with similar taste to you. Most of the online review sites allow users to check out other reviews that another user have posted. Try to find people that have similar taste to you. If a reviewer has posted a negative review for your favorite restaurant, it's likely that you won't agree with other reviews that user has posted. Find someone who likes what you like.Look for keywords or phrases in a review. When reading a review that starts with "This is my first..." it's probably safe to assume that the user is not a expert on what they are reviewing, and that you should read the review with a grain of salt. Conversely if a review begins with "I've been doing/buying/using something for years..." then the reviewer is more likely to know what they are talking about. It's also helpful to find reviewers that have the same level of experience as you, since they are more likely to notice the same things as you do.
Screw the reviews. Online reviews aren't the be all and end all of everything. Sometimes you just have to follow your own instinct. There's a new restaurant down the street that hasn't been reviewed yet? Why not give it a shot. Don't let reviews run your life, maybe you'll find something that no one has found yet.