To add to what jtara posted make sure to use a tripod, any movement or noise will eat up bitrate on video so you want to minimize this as much as possible. Having a steady cam helps quite a bit, while on the subject turn the steady cam feature off on cams when you using a tripod. This is helpful for hand held shots but effectively reduces the resolution of the cam, you don't need it you're using a tripod. Once you get this masterpiece on tape what you do with after that is important. One of the basics to understand about any digital video is the more you do to it the worse it gets, there are exception such as if you're working with very noisy VHS captures where minor filtering if done properly can have very beneficial effects.
Typically you're source is going to be a DV cam. Transfer via firewire as DV-AVI. Note that using the USB cable for transfer will produce a web quality video. Trnasferring as DV-AVI over firewire is a bit for bit copy of what is on tape, very similar to copying a file from one folder to another with the exception being there is no error control. i.e. if your computer is not fast enough or access's the drive while you're doing this it's possible to drop frames.
Import your DV-AVI into your editing program and make all your edits. Exporting directly to the desired format is preferable but if you're editing application doesn't support that export as DV-AVI. Any quality video editing application will only re-encode the frames that are necessary such as where you have added transitions. DV-AVI can be re-encoded multiple times with negligible effects on the quality.
Always go go back to the source to produce new material, if for example you have already encoded your DV-AVI to a highly compressed format like WMV and decide you want to add some text titles use your DV-AVI project for this. Do not use the WMV as a source.
One thing to be aware of is footage from a cam is interlaced which is designed for playback on a TV, it looks quite bad on computer monitor during playback if you are not using a software player that supports deinterlacing on the fly. If you have ever seen video that that appears to have horizontal comb lines during fast motion you'll be aware of what I'm referring too. You are either going to want to deinterlace it or if possible use a cam that will shoot in progressive mode. Progressive mode is found on higher end models. On a side note, deinterlacing is destructive process because any filter that performs this task basically throws half the resolution away, you only want to do this to video you intend to be viewed on progressive display like monitor. Any footage intended for TV viewing should be left interlaced.
Upload the highest quality video you can to youtube, they re-encode nearly every video. You want to provide them with the highest quality source possible, make sure you are using a resolution higher than what they are re-encoding too. Scaling video up produces very poor results under any circumstances.
Lastly you can match the specs that youtube wants but you won't find these specs on their site that I'm aware of. There is certain set of conditions that prevent them from re-encoding the video which will give you control over the final quality which is ideal. If you really want to you can "trick" their software into thinking the video meets their specs by altering the header, this will allow you to upload a video with higher bitrates and resolutions than they allow.
