Before using the SEM on campus you should read the SEM entry in wikipedia and learn about:

• Scanning process and image formation (note that beam energy and interaction volume are a critical parameters when imaging single wall nanotubes)
• Sample prep (importance of grounding the sample)
• Detection of secondary electrons/backscattered electrons (secondary electrons are typically used to image CNTs)
• Resolution of the SEM (depends more on the size of the interaction volume, rather than the beam spot size)

For good, practical, advice about tuning the aperature and stigmators see this webpage.

This paper from Michael Fuhrer's group has useful information for seeing single walled CNTs: “Rapid Imaging of Nanotubes on Insulating Substrates” T. Brintlinger et al. Applied Physics Letters 81, 2454 (2002).