Basically, a handstand is the ideal balance. The wrists are the center of the scales. Ideally, keep the whole body above the center of the wrist. If toes fall, quickly form an angle in the shoulders, try to balance the structure and turn on the deltas, pressing back into the handstand.
Your inner feelings are sure to prompt you this option.
Toes fall over your head – push your chest forward, turn on your abdominal muscles, return to the stand. Balance, in my opinion, is one of the most crucial skills that need to be fairly trained, hence, take the time and patience for this. Exercises to help you with the balance, see here.
Remember: you can not only stand, but also walk. Are you losing your balance? Take a step.