Want to tie somebody up? Have some scissors on hand in case you need to get 'em loose in a hurry. Bandage scissors can be slipped beneath a rope without risk of cutting the skin. And for God's sake, make sure you have a key before you try on those handcuffs!
Have all the necessary props for the scene at hand and in working order. If you are using props, make sure you know how they work, and if it is something the partner needs make sure they have it and know how to use it. Make sure your location is secure, or appropriate to the play.