Loki mostly spends his time making stupid speeches so that a hero can clobber him (metaphorically or literally) as a punch line. What precisely Loki means to do with Earth is never certain (which is why it isn't interesting either,) and his "plan" to distract attention by being taken prisoner is rather like planning to win a fight by breaking your opponent's fist with your chin.
Loki's plan was to do exactly what happened. Primarily unleash The Hulk and hope he tears everyone to shreds inside the Helicarrier. Hell, as an extension of that he also WANTED the Avengers to track him down in New York because he thought there was no way he could lose with his army and not only would he take the world he'd de-moralize eveyone by seeing their heroes defeated.