If its me, I'll send my players from best to worst when it comes to penalties. You can probably workout all kinds of scenarios, but at the end of the day it comes down to pressure. If you keep putting them in the back of the net then you keep the pressure on the other side.
You also avoid a scenario were your best player doesn't take a kick at all.
The problem with this is that sometimes players don't feel they can take a penalty kick, now you don't want to force a guy to take a penalty kick.