What is 'very cold' ? I have found that a C182 (old one with 12v system) starts easily in just above zero deg weather if you pull the prop through a couple of times before starting. However, beware! and
see this thread for caveats !
In my particular case, no primer at all needed, just a few quick squirts with the throttle while engaging the starter. That said, all engines are set a bit differently, so you may have to experiment a bit.