i tend to pair on size yes big to small , some are more front ended others more rear ended and not as nicely tapered , others are long cast some can seem cobby so pairings the later would result in better shaped birds , then theres the eyesign believers dark eyes to light eyes opps forgot most dont like same eyed pairings but i have paired mother to son with same eyes and won with them , if you use this template your birds start to look like one another breeding a nicer type of bird . When pairing pigeons i tend to pair birds that will compliment each other.