Depends on your budget, what are you using at present?
The old adage rubbish in rubbish out is the start, so for best results you
need very good video footage.
You import this to the pc as a dv-avi file, doesn't matter with what.
Edit and save as a dv-avi file.
This is now important, the compressor that makes the mpeg2 file is critical
for best quality. You can choose from ones that are bundled with the dvd
authoring apps, and generally the more you pay the better you get.
I personally use canopus products, something like procoder will set you back
£300, superb and then I use Ulead dvd workshop 2 to author the dvd and
create ac-3 audio. You can pay several thousand pounds for apps which will
have 7 or more passes when encoding if you want to approach the commercial
side of quality, or workshop has a decent encoder anyway and at around £200
is good value.