I tune all of my AEGs for faster trigger response, and rate of fire goes up with this as you are effectively shortening the time it takes for one complete cycle of the gearbox.
The easiest and cheapest way to achieve this is by installing a mosfet and running an 11.1v lipo. You will need the mosfet to prevent the trigger contacts burning out from the higher voltage output of the 11.1. Even faster trigger response is possible with the 11.1 & mosfet, high speed gears (13:1 ratio), a high torque motor, 16awg wire and short stroking the piston. The second route requires more work and tuning, so my advice would be to try the 11.1 and mosfet first, as this is sufficient for most people.
Accuracy is a bit of a redundant word in airsoft. You're chucking a round plastic BB down a smooth barrel, you're never going to achieve pinpoint accuracy with those factors. What is important is shot to shot consistency. Consistent FPS and consistent hop with a quality inner barrel and good quality BBs will give you a more consistent BB flight, allowing you to better determine where your shot will land. To add to what Noobtoobe mentioned with upgrading the compression parts, installing a metal cylinder head with a double o-ring and a nozzle with an o-ring will go a long way to improving FPS consistency. They are the first thing I change out when I buy a new gun/tech a friend's gun. I find that usually the stock cylinder, piston and piston head are fine, but if you want to change them out while you're at it then go nuts. Just remember lighter parts move faster, so avoid metal pistons/piston heads if you want the most speed out of your setup.