Ways to scale pixel images without blurring and distort?

[The Game]

I wanted to try out pixel art, so I got down and did a nice image not knowing about size and knowing what the image will look like in 100% zoom. So now I have an extremely small alien sprite I'm not happy with due to its size. How can I scale it up a bit without blurring and large, unwanted distortion? Thanks.

[The Game]

And yes, the alien is my current avatar.

[Sarkut]

How much do you want to scale it up?

[The Game]

Honestly, I'm not sure. At least to the point you notice the pixels break on the tip of his head.

[Sarkut]

Scaling up in multiples of two will likely cause the least distortion.

Is doubling too much?

[Simon Brown]

Scaling up in multiples of two will likely cause the least distortion.

...as well as choosing "nearest neighbour" as the sampling method.