According to the OP, Gaara knows of Itachi's hype, which would mean that he knows Itachi is able to cast Genjutsu with a finger alone.Gaara knows nothing about Sharingan: Genjutsu. What he only may know, are Ōnoki's words where he instructed the youngsters not to look at his eyesYou must be registered for see links, but further upon that Gaara has pretty much no intel on Itachi's genjutsu prowess. Would you dare to say he wouldn't fall for Utakata? No, impossible. Whether he is more careful or not is irrelevant, because he will either be caught in his genjutsu anyway or Itachi unleashes Amaterasu which will hit regardless Gaara sees it coming or not.
In an area where there is a lot of sand, Gaara could manipulate the sand in a fashion to where Itachi is unable to see him. EX: Hiding in a dense sphere of sand, which Itachi can only penetrate through the use of Susano'o which Gaara would be able to pull him out of.
This would make techniques such as Genjutsu, Amaterasu, Goukakyuu etc ineffective.