Yeah there are some golden rules on pull-starts. Never pull them all way out. I try to only pull half-way out. Use quick wrist flicks , dont use your whole arm.
I also try more than one way to pull-start a motor. I vary all things , speed , frequency. I sometimes do a slow and steady pull and at compression a quicker flick , after a bunch of hard pulls if its not firing , then speed up the slow and so forth. You gotta listen to the motor. Saves your arm.
Also if you use a handheld glow-start. Make sure its always fresh battery. Rechargables help save money and can always be peaked for first start of the day. Otherwise I find handheld glow-starters a big problem. I switched to the 1.5V Hobby Battery. Its a life saver, lasted me a couple of months and is pretty inexspensive. You can start motors all day , break them in easier and have less frustration if you use this style. I reccomend these 100% over regular hand held.
This will eliminate one of the main causes for a motor not starting, which in return will equal less use and abuse in most cases on the pull-start. When your frustrated , the pull-start takes the abuse and is probably when your going to break it by pulling it to hard or fast.