For PC games, demos. For wii games I'm forced to rely on word of mouth, reviews (IGN, amazon, metacritic) and if I'm lucky a friend will have a game and try it out.
I wish nintendo would allow Wii demos, I would happily buy a Mag for a DVD full of playable demos, personally I think they are nuts not to do it.

Sometimes I rely on reviews when deciding what (or if) to buy. However, when I rely on reviews I tend to ignore the final score and just focus on the main points that they are trying to get across in the review.

As for review sites, I find the reviews at Game Revolution to be somewhat aligned with my thoughts on a game.

Edit: Word of mouth is pretty big for me too, but only when it comes from someone whose opinion I value.

i base them a lot on reviews. I never used to but i do now.

Reviews are the main reason i got so hyped about GTA4.......and they're the main reason i WON'T buy Haze.

Theres some games that are must buys for me (GT5, KZ2, Res 2), but for more "unknown" games, i make sure to check in on IGN and Metacritic.

reviews are important - just don't get too hung up on the actual number assigned to a review. actually read the whole article. also, it's good to develope a "relationship" so to speak with a particualar reviewer so things are in context. personally i trust penny arcade, yahtzee, ign the most.

Yes. Here is basically the cycle:

1) Here about on VGChartz.

2) Watch a few videos and see a few pics to see if I'd like it.

3) Read reviews. If it is praised, I buy the game.

Not reveiws alone, but generally use metacritic as score along with my own interest. If I really like a genre I might add as much as 20 to a score when comparing two games deciding which to buy, and if a game doesn't sound interesting to me, I might subtract as much as 20 from a metacritic score. I also use amazon if it at least 20 votes, and will generally read a few of the highest and lowest scoring reviews listed from metacritic.

I also look at the top ranked games on metacritic and consider some of those if I hadn't already... Sometimes I will get a low scoring game anyways, especially if it's price low.

I'm wary of the validity of reviews for supposed good games that are rated low or good games that are rated exceptionaly highyl.

Apart from that reviews generaly aren't too bad , I wouldn't base the purchase of a new game for it but if i'm looking for some hidden gems on the PS2 I might search reviews.

Yes I do but I have a limited budget and most of the time, I happen to like the games I buy

If it has like 60 or lower average score on Metacritic I won't buy it...

I read the actual reviews and then hop over to Metacritic/GR, lop 5 points off the score, and decide whether I want the game or not.