like arduan3 said, you make the doll in the likeness of said person, hopefully get some sort of personal item [hair/clothes/nail clippings] and stuff the doll with them along with herbs to aid in the desired intent. [healing, hexing, love] in this way, yes, poppets are a strong and effective form of magic.
the problem however is societies view on poppets. thanks to the common knowledge of voodoo practices, people believe that any doll in their image means you're cursing them. this is, of course, not true at all. even the needles, you're charging each needle with intent. say someone has a bad back, you charge the needles with healing energy and stab the spot where the pain is. pull out the needle, and hopefully, the pain will be less, or gone. while i don't work with poppets, i do see it as a strong and effective form of magic, just has a lot of misconceptions with it.