We'd need to know the aperture, shutter speed, film speed, and local lighting conditions to offer opinions on that. Of these four factors, you've only mentioned the film speed and strongly hinted at the lighting conditions. One useful rule of thumb is the "sunny 16" rule: In full daylight (no clouds, no shade), set the aperture to f/16 and the shutter speed to the reciprocal of the film speed (for instance, 1/400s for ISO 400 film). In practice, of course, most cameras lack a 1/400s setting, so you'd probably use 1/500s or 1/250s. In extreme northern or southern latitudes, this rule may be a stop or so optimistic even in broad daylight. The required exposure also goes up surprisingly rapidly when you move into shade, cloudy conditions, the time after sunrise or before sunset, etc.
