I'm no expert on clean-ups (although there are a few tutorials around which can help - a search of this sub-forum will yield some results!) but I do a few basic things that might help.
1) Select small parts of the pic using the Marquee Tool and blur/modify one small section at a time, rather than trying to do it free-hand with just the blur tool (the marquee will limit the area you can modify, protecting nearby parts of the picture you don't want to touch). By contrast, you can also selectively sharpen other parts of the picture as well. Sparing use of the Smudge Tool (combined with the Blur Tool) can help clean up blotchy areas too.
2) Resize the picture - making the picture a bit smaller can create the illusion of sharpening things up a bit. The default image resolution of 1280x960 px is usually too big to be able to view comfortably on the forums anyway, hence I usually scale my pics down to a width of 800 or even 640/600 pixels, depending on the shot.
