more you have the more compromises you will have to make. It’s sometimes good to go with the old adage of a narrative Start, Middle and End, taking the viewers on a journey.
What format will I need? Some variables should be addressed from the outset while overlooking or leaving them to the last minute could be expensive. If the video is mainly for Europe, PAL is the system in use while in the USA, NTSC is universal? Do you want it in widescreen or 4:3? This could be a stylistic choice but if you wanted to incorporate it into a power point it will look better if it fits with the rest of the presentation. Do you want it on HD, HDV, DV or Film? Do require music and if so do you need to clear rights or commission a composer to create a original score? At the end of the production do you need your video in Mpeg4, WMV or another DVD format?