If explaining an activity in a retrospective takes more than a minute or two it probably isn’t very effective. Don’t fall into the trap of making things too complex. Activities shouldn’t be complicated they should be fluid. Giving participants too many options and being unclear with instructions makes it difficult to fluid with sharing thoughts.
This tends to frustrate the participants and make them disengage. Good facilitation makes sure everyone has high energy and is actively participating. Be sure that you come prepared and articulate with clarity and brevity what you want during activities. If something isn’t working don’t be afraid to adjust it on the fly. Make it more simple and keep the flow going.
Remember to retrospect on your performance regularly, it is the quickest way to improve your facilitation skills.