1) Make the video dimensions the same size as the flv encoded output will be.
2) Do not try to compress too much. If it's going to be recompressed anyway, why add the extra distortion? The flv output may actually end up smaller due to less distortion in the original. Compressors will try to preserve any distortion allready present, sacrificing file size and/or quality to do so.
3) Make the frame rate about the same as the flv will end up. 15fps is fine for net video.
4) If you simply must make the file small as possible, then scale the dimensions somewhat larger and add a little blur to it. This way the overall distortion will be less since the sharp edges are reduced. By the time it get resized by the FLV recompression, the edges will look good again.
Fav quote - "Experience is whatcha don't get 'till ya don't need it no more."
System - Athlon 1.4GHz, Win98, Hauppauge PVR250 receiver and compressor.
Software -Magix Movie Edit Pro 10, Nero 6 + NeroVision Express, Moho 4.61, PSP 8.1, Bryce, Quicktime 6.52 pro, Goldwave 5, DVD-Lab.
Cameras - Panasonic GS9, Canon ES8400V, Canon EOS D20 and Canon A70