Works for me
Sunday was pretty cold I had the first start of the day on a club 150:
Throttle 1/4" open(don't think it matters much at this stage),mixture full rich.Keys in (so you can start cranking immediately after priming),5 full primes (allow time for primer to refill),2 full pumps of the throttle,1/4" throttle and instant start.
I also like to pull the prop through a few blades to break the stiction that can form before starting during walkaround (check keys out,throttle shut,ICO and park brake on,chocks if poss).Try to finish with the prop pulled back against compression so the starter motor has less initial resistance (do not turn engine opposite to usual direction as this can knacker the vac pump vanes).
Warm start then just 2 primes,2 throttle pumps.Works ok for me these days.
I got quite hung up about starting after a couple of failures but this turned out to be poor battery/plugs at the end of their life/mags due overhaul.
MM