I generally have my SAR group take vitals on each other. Take a pulse, move to the next person, take another pulse, over and over again. That way they get used to finding the pulses on different anatomy. The repetition works. Also, if the numbers are not anywhere near the same, you can try having them take the pulse on two different arms of the same person and count out loud the beats. Part of this is learning what to count and what to listen for.
In SAR, are your students EMTs or merely FA certified? When teaching layperson FA I generally teach that it truely doesn't matter if the pulse is 67, 68 or 72.. but is it 40 or 140? Does it stay the same or get faster/slower? Some can get so hung up on being perfectly accurate that they blow it.
In counting respirations I've always been taught and taught myself to count respirations with a scope while supposedly counting heart beats. If you tell the pt you are going to count their breathing, the breathing becomes conscious and weird.
Rid has posted an awesome BP taking lesson plan which I have shamelessly stolen and used repeatedly.