Some tips for shooting slide film (
aka reversal film):
-Slight underexposure will result in deeper color saturation. Note "slight" underexposure; no more than 1/3 of a stop under. As has been mentioned, reversal film is not as forgiving, in terms of exposure, as negative film. But all this really means is that you're "stuck" with the exposure you choose when shooting. Meter carefully.
-The conventional exposure advice for negative film, "expose for the shadows, print for the highlights", does not apply to reversal because, obviously, there's no printing process. As such, be very aware of the contrast range of your film stock. If you start metering for your subject's shadows, don't be surprised when you lose detail in your now blown-out highlights. Shoot tests, if possible; you need to learn to previsualize the contrast range of your photograph.
-Since there is no printing step, and therefore no chance to color correct your photos, you must be aware of the "balance" of your emulsion; i.e. is it calibrated for tungsten light sources or daylight? Most film you'll buy over the counter is balanced for daylight. So if you don't want an orange cast to any photos taken under tungsten light (or a green cast to any photos taken under fluorescent light), you will have to get a blue filter (or a magenta filter to correct for fluorescents) for your lens. The most common blue filter is called an "82" filter.
-Subject your friends and family to interminable slide shows frequently. They'll love it.
Enjoy!