Exporting 640x360

Hi everyone. Hope you had a nice holiday. I need to export some Nutcracker performances to upload onto vimeo and youtube.  The files will be massive so I want to go with the 640x360 setting since these are more for the clients to review. Could you please advise on the exact tweaks to the export settings to make sure the 360p is crisp and clear?  Main reason is that I have a 5GB limit on vimeo and so I'll likely run out of storage space before I have everything uploaded. I had to export some 360p a few weeks ago for someone else that had been shot at 1080p and the results didn't look very good so I feel like I must have not had the proper settings. Thanks!