Generally the larger the breed the harder it is for them to fly but if you need to clip the wings only do one wing, not both. It's easiest with two people. Take a sharp pair of feathers, hold the bird firmly with it's head under your arm, spread the pinion feathers (last eight or nine feathers which look like fingers), snip them off by 50%. It doesn't hurt the bird and causes it to flop over if it tries to fly. This needs to be repeated annually after moulting. Good luck!