Interesting discussion and plenty of good info here. Just wanted to chuck in my tuppence, for all it's worth, which isn't much, but nonetheless.
Cold starts can be frustrating but if done properly are no worry. Someone earlier commented that we don't get exceptionally cold temps here in the UK, and that our "cold spell" lows of say -5C aren't that low. The truth is, as most car owners will know (especially those of us who have operated older ones), anything approaching freezing and below is enough to reduce the charge in the battery and thicken up the oil enough to make starting problematic.
A couple of winters back during a chilly spell not unlike the one we've just had, I took out a Tomahawk for a flight on a lovely clear crisp morning teh week before Christmas. the aircraft had sat unused for two weeks due to bad Wx and the temp had not been above -5C over the whole of that period, and the ambient that morning was at around about that temp. I knew that the battery would probably be flat as a pancake and the oil not exactly free-flowing. Gingerly pulled the prop thru a couple of rotations, could tell the sump was like jelly. Thought I'd give it a shot anyway but wasn't surprised when the prop lazily slopped round once, stopped, then twice, and stopped again. Gave up right there as I didn't want to knacker the starter and besides it was clear this lump wasn't going to want to wake up right away.
Ended up getting out the generator & heater & stuck it on, meanwhile removed the battery and trudged back to the club, stuck it on the trickle charger for an hour. After then, 6 primes and two attempts got it started nicely.
Have found through experience that leaving anything up to 30 seconds after priming before turning the starter gives enough time for the primer nozzles to fill. Each aircraft seems different but leaving the primer out while starting & pushing in when the engine fires seems to work every time.
At the end of the day flying's only as difficult as you make it, as with all else preparation's the key...
Smithy