It depends on the final target player. If you only want to play a DVD on a standard player/TV then securityman's suggestion is OK.
If you want to play on an HD TV and let upscaling from the player be used then you need to set the quality setting to highest and the bitrate to the highest possible - these are found when you click the Encoder settings button on the burn dialog. MEP will ask you to correct the bitrate if the video is too big to fit on a DVD.
For full HD then you need to burn a BD disc - your source material should also be HD - the standard settings for HD are normally satisfactory.