First of all, create or select a high quality video with clear resolution. Smaller video with clear resolution is always a better choice than larger ones with high resolution as the small ones take less time to get downloaded. While uploading videos on your site, make sure that you have enough disk space and you are allowed to use maximum bandwidth as these videos really consume a lot of bandwidth.
I have seen many of my friends who neglect the audio section of a video, which is absolutely wrong. The audio clarity plays a vital role in a video as far as quality is concerned. So edit the sounds of the videos separately with some efficient audio editing software before you upload it. No viewer will be attracted to a video with a poor sound quality. Along with the sound quality checking, video compression is also important. If done efficiently, it can improve the download speed of a video without hurting qualities and other parameters so much.
The video sharing procedure sometimes requires usage of some video editing software. But don’t worry. Anybody with no or very little knowledge in video editing can use them. Adobe Premiere Pro CS3 is one of the best packages for this. But it is a bit expensive at the same time. If you cannot afford, you can also try the less expensive counterparts that are available in the market.