The best zucchinis are the small tender ones (5 inches and under);  anything over 8 inches is fit only for stuffing.  Look for smooth, unblemished, deep-green skins with faint stripes or specks of gold and no withering at either end.  Refrigerate in plastic bag for up to 4 days.  Be sure there is not moisture in the bag. 

To clean, scrub zucchini gently with a asoft rush under running water.  Slice off both ends.  Do not peal the edible skin.  Zucchinis can be baked, boiled, grilled or stir-fried.  Tiny zucchinies are good raw, with just a drizzle of olive oil.