A friend of mine who was turned down recently for a job tried to figure out where things went wrong, and he found part of his answer in looking at his application. He made some innocent mistakes that he hadn’t caught, but the interviewers apparently did. The best way to avoid this is to fill out the application when you can give it your full attention without getting distracted. The next step should be to print out the final copy and write the name of the intended airline across the front page. Set it aside for at least a day, maybe even two. Then, when you are again able to give it your attention with no distractions, go over it line by line to make sure everything is correct. One way to slow yourself down and force yourself to notice any mistakes is to read it out loud, pointing to each word like a young kid learning to read.
Once you’ve done this and found any issues to rectify, print it out again with corrections, and have someone else read it over for you. The best strategy here is to ask someone to read the application who is totally unfamiliar with it, so that they are forced to slow down as well. Once someone has read it or been exposed to it, they are likely to rush through it on a subsequent reading and can too easily miss an error.
Common mistakes are incorrect expiration dates (passports, medicals, etc.) and overlapping dates for jobs you did not work concurrently. Any extended periods of unemployment need to be addressed as well. Address changes need to be accurately recorded. If you have a resume specific to aviation, you should compare the relevant sections on that to your application, and have your proofreader do the same thing. Everything needs to match up. Verify that the phone numbers and emails you supply are accurate and working.
The most important thing is to be honest. Don’t lie or embellish! A pilot at a legacy major in the not-too-distant past got terminated when it was found that he had falsified military service on his application. He also got to spend some time talking to the FBI, and he has likely squandered any hopes of ever flying professionally again. Assume that anyone and everyone might (or will) take an effort to verify your credentials and education.
Applications are time-consuming and tedious, but they are also a necessary evil. Do yourself a favor—read all the instructions as you go along and triple-check all your entries. Once you hit submit, the only changes you want to have to make later are to your flight times, not basic factual information that should have been correct the first time.
Finally, once you’re satisfied, keep a hard copy on hand in case you ever need to reference it again, or heaven forbid, the site crashes and you need to re-enter everything.