The most useful tool is a swash-plate leveler, it takes out a lot of the guess work, Leveling the swash-plate correctly is probably one of the most important aspects to setting up a heli, it makes the difference between one that will hover nicely or one which will either never get off the ground (or if it does then it will usually be followed by a crash fairly quickly) Also level and balance the main blades. Its useful if your new to set some extra expo in the TX as well as it will make it a bit less sensitive on the control inputs. I have a blade 400 and dxi - not flown it for about a year now though, it takes a huge amount of patience to learn to fly these, so take very small steps. It is worth putting in the time as when you can hover it for a whole battery you will feel like a pilot god!