If you are using an SLR, a long focal length telescope and a tripod, then shutter speeds of 1/30th of a second are fine. Use a low ISO setting to reduce noise and underexpose slightly to prevent bright details burning out.
For detailed mosaics you can reduce the effects of atmospheric turbulence by capturing high speed shots. I take a series of audio/video interleave (AVI) files, since it is easier to deal with a handful of AVI files than thousands of individual shots.
To do this, start at the terminator line and set the focus. Zoom in on the image and ensure it is as sharp as possible. Set the exposure and move around the rest of the Moon’s surface, checking the camera’s histogram and adjusting the shutter speed and camera gain (sensitivity) until there are no saturated areas. Your settings will probably give exposures of about 30 to 40 frames per second. Although these may make the shadow section appear very dark, it is better than having other overly bright areas.
Head back to one end of the shadow and capture the first AVI. Load the file into a manual stitching program like iMerge and move the telescope to the next small section of the Moon to build up a rough mosaic. In total I record a series of about 25 AVIs, each of 1000 frames.