on the final file just a bit filters//sharp//sharp that will help only use it once maybe 2 if u think looks better

png

Exactly what iLegit and xXDreamAlongXx Said,

Filter > Sharpen > Sharpen

Save the file as a PNG Always when transparent.

Worst case scenario you transformed the render wrong and that could also cause the blurriness my friend.

Don't just sharpen then leave it. That usually over sharpens. After you sharpen go to edit > fade sharpen and lower until it looks nice.

Also use imgur

Save it as PNG or on the highest quality for JPEG (if you don't already, when you save something go to "save for web and devices" under file and it gives you more options)
Also photobucket and imageshack are the best sites, imgur and tinypic lower the quality