Are the leaves opposite each other on the twig? Hint: a missing leaf may make leaves appear to be alternate. Look for a bump or scar where leaves were attached, or look to see if twigs are opposite each other where they attach to the stem.
Are the leaves alternate (not opposite each other on the twig)? Hint: some species have alternate leaves attached very close together on short spur shoots. In that case, look to see if twigs are alternate where they attach to the stem.