First point is that a 2M print wont generally be viewed that close, but I understand what you mean.
The best advise I can give is don't over process the image. ideally I'd shoot RAW as this stops any of the cameras inbuilt sharpening being applied to the image. Next I would only add a modest amount of capture sharpening to the image. Don't over sharpen as most output devices also add sharpening. Multiple sharpening process can really screw up the image. The same with noise reduction, only use it if you need to as it can lead to loss of definition. Some programs are better than others in doing this.
In general I wouldn't re size to the final print dimensions as the printer software will do this for you and may make a better job of it, but ask the printer for their advice.
Finally save as a TIFF if you can, no compression artifacts, although I would say the results I have had from low compression ( Photoshop 12) JPEG's have been fine upto A0
