First, I would say design your primers so that the amplicons are of small size. The bigger the product you amplify, the more chances you are going to pick up NUMTs.

Also, BLAST primers against nuclear DNA.

I may add also when you design primers Plz always see that the forward and reverse primers will not form heterodimers by them self. plz keep 3' last 5 bases of promers free from self or hetero complimentarity

Please, check the attached docs!