Trim dead time first, then choose dimensions and bitrate appropriate for the place the video will play. A phone feed may not need the same resolution as a desktop tutorial, but small text in a screen recording may require extra clarity.
Export a short representative section with the video compressor and inspect motion, text, audio, and dark scenes before processing the whole file. Compare file size with visible quality and keep the source. Lowering bitrate too far can produce blocking and blurred lettering.
The smallest file is not necessarily the best shareable file.