Precariously is not usually a positive thing. If one is precarious you are on the edge, possibly toying with danger. He teetered precariously on the edge of the crevasse. This is quite precarious...
Words may have more than one antonym, according to which of its meanings you refer to. Precarious (literally "dependent on prayer") means 1 dangerously unstable, 2 subject to chance or unknown...