Considering there have been websites that have been known to be paid off to give good reviews (IGN comes to mind), I never trust any initial reviews, at least, not from the so called "experts." There've been many games that I've played that are mediocre that have scored near perfect reviews, and others that are some of my favorites, but scored a 3 or 4 out of 10. If it's a game that I'm semi-interested in, I'll wait for a few weeks until the general public gives their opinions on it. If everyone's saying that it's a really good game in spite of so-so reviews, chances are I'll probably pick it up.
I also try doing a lot of my own research too if I'm on the fence about a game. A big thing I used to do (not so much lately) was go on YouTube and watch multiple user reviews about a game, and videos of gameplay footage. It's also why I miss being able to go somewhere like Blockbuster to rent a game- I won't feel as bad paying $8 to try a bad game for a few days than paying $60+ on a new copy, only to have it collect dust on my shelf.