It`s even to risky online, I often tried to steal blinds and mostly even lost to one player with big blind. I noticed that I try to "bluff" more when I am late in tourney, I think I need the high blinds. It`s best to have a high stack so you needn`t bluff.
But with bad cards and when it`s not needed I only bluff when I don`t want to play a freeroll anymore.