Until then, they should work on making simple poisons (from household chemicals and such) and bombs and sharpening their knives. A gang of a dozen students could probably drop a few security forces if they got the drop on them and used knives quickly. Kill them, take their guns, run like HELL, and repeat as necessary.
It would help the 3-person teams a lot if there was some group smuggling rifles into Iran, because taking them from security forces/foreign Arab pro-regime mercenaries is not easy (although it's doable). They wouldn't need assault rifles, just some old bolt-action dealies to take out guards from a distance.
If the government is unable to maintain order, what does it actually provide to the Iranian people? That's the only thing it has to offer, and if the students take it away, it will fall.
Last year, the "DC snipers" (Mohammod and Malvo) had a long-running spree in the area of the US capital, with a huge chunk of the FBI and local police looking for them. If they hadn't started sending stupid notes to the cops, and calling them up on the phone to get payoff money, they might still be at it.