The key to being consistent is the word "rigorous". To a certain extent, education does help. There are also certain natural abilities that one might posess which might help as well.
However, the true key is being "rigorous". Constantly read, constantly listen, test and re-test your concepts, do not give up (ever), plan, research etc.
There is a certain amount of labor that comes with any job whether it be being a mechanic at a dealership or an engineer at Boeing. At any one of these jobs, every person is being "rigorous" as that is their trade.
However, if I am a mechanic at a dealership and mess up on your car, Im not going to empty the bank. Therefore the amount of rigour you need to have is on average much higher then a person at the regular job.
Whether your very experienced or have no experience, you need to be reading. You need to be planning and constantly learning.
Dont worry if you mess up at first. Learning to play a musical instrument does not take one day, but many years of practice. Some people will learn to play the trumpet in a few months, others several years.
Bottomline, think "rigorous". You need to be more rigorous then a mechanic or an engineer at Boeing. There is no insurance policy or large corporation insuring our work. The buck stops here. If your not willing to be rigorous then its time to get a regular job...