For an easy way to cook it I echo what Electrongirl said. Marinate it overnight and stir fry it. Another option is to dice it, marinate it overnight, and place it on baking paper to bake in an oven on moderate heat until golden. It makes it slightly puffy and crunchy. That way if you add them to a bowl of stir-fried vegetables they keep their shape and provide a slightly different texture. You can toss them in rice flour with some sesame seeds before baking them as well to make them extra crunchy and golden.
You can also buy pre-marinated tofu in most supermarkets. If you're worried about cooking it for the first time just buy some of that, dice it up and add it to a salad or stir fry.
And if you don't like it the first time, don't give up on it! There are so many ways to prepare tofu that another method might please you where the first one failed. You can freeze it beforehand to give it a firmer texture while stir-frying it, you can scramble it with herbs and use it instead of scrambled eggs on toast, or you can add it to smoothies to add protein. You can even use it in deserts! Yep, there are a few recipes for tofu cheesecake out there believe it or not!
http://www.fatfreevegan.com/desserts/br ... cake.shtml
There's a great recipe for tofu mini-quiches at the Fat Free Vegan Kitchen website. It's really, really yummy but not that easy to make unfortunately. But it's worth the fiddliness in the end! And it's no harder to make than normal quiches as far as I can tell.
http://blog.fatfreevegan.com/2006/12/mi ... iches.html