Why does Final Cut Express make videos low quality?

I have been editing videos off my home video camera for a while on FCE and it has appeared very low quality. Originally I put this down to my camera's quality, but I have now got a Nikon D5100 (true HD) and I still have the same issue, also the video generators are coming out the same. Any suggestions on how I can make it good quality?

"Low Quality" video can be defined many ways… This includes graininess because of low light, too much panning or zooming when the video was captured, focus problems, too much compression after editing and exporting to a finished product… And LOTS of other reasons.

We can't see what you see. It is impossible to provide any specific recommendations.