Many students did not answer the question as to why the intercept of the P vs. 1/V graph should be the air pressure reported by the National Weather Service (as a negative number). Think about this and figure it out now, if you did not write about it in your report.
Some students were still not sure what the difference between an inverse and a direct proportion. Go look this up on the Internet and study it until you understand it.
PV = k is only true at constant T and n—was T in fact constant? Probably not, compression of a gas heats the gas (work is converted to heat). This heating could have affected the equilibrium volume you wrote down.
The P and T involved in your experiments in this lab were not extreme enough to need to invoke the van der Waals equation. Work out what the deviation would be for nitrogen for the pressures and temperature in the experiment. (Nitrogen is the most abundant component of air). Don’t forget to add the barometric pressure to your experimental pressures!
Vagueness is the refuge of the ignorant or lazy student. Don’t be vague! For example, do not write something like this: “We maintained some factors constant while having variables.”
Don’t talk about “human error” unless you can specifically identify a problem. Again, avoid being vague!