For a fixed pitch heli the throttle curve should be left as default - linear from 0 to 100%. It is not necessary to check the headspeed because you are unlikely to exceed the maximum headspeed, as the heli will take off like a rocket if the headspeed is too high.
For a collective pitch heli you should get a tachometer to measure the headspeed. Borrow one from a friend if necessary.
For the next step, you will need to know your desired head speed.
Hornet CP: 2000-2200 rpm
Piccolo CP/Pro: 2000-2200 rpm
ECO 8 1400-1800 rpm
Logo 10 1400-1800 rpm
Most microhelis will have a nasty wobble below 1800 rpm, and most non-micro helis will have a nasty wobble below 1400 rpm. If you can't reach the proper head speed, you should buy a new pinion with the proper number of teeth before proceeding. With a collective pitch heli with a five point curve on the transmitter, it should be set to roughly 0-50-x-x-x where x is the throttle position at which you have the desired headspeed. For a collective pitch heli with a three point curve on the transmitter, it should be set to 0-x-x where x is the throttle position for the desired headspeed. If x is not between 85% and 95% of throttle, you should select a different sized motor pinion because the motor will not be running efficiently which will decrease your power and flight time. For a detailed explanation, see Section 23.9, “How ESCs work”.
Note: If you have a Futaba radio and a Fusion 35 ESC, then you may have problems properly arming the ESC. If you have this problem, then try increasing the throttle range to 125% so the low endpoint is lower.
Note: If your radio has knobs on the face, then it is likely to have an option called "Hovering Pitch" and "Hovering Throttle". This option is used to fine-tune the throttle and pitch on nitro helicopters for changing weather conditions. These options will put a strange bump in your pitch and throttle curves when the corresponding dial is turned. You should disable these options for electric helicopters since this is not required.