I don't know if this has been said by anyone here, but please regard the following:
This is my unsolicited advice to anyone going for T/O or any Operating position within MTA:
Please, please, please have ALL of the documents they ask you to bring the first time and all times after. Not having them WILL jeopardize your chances of being processed further, i.e. hired.
Also, please, please, please make sure your health is in order because the doc's WILL put you on medical hold for high blood pressure or diabetes or anything else that seems wonky to them. Eat right and find some sort of activity that develops your lung and heart capacities.
DO NOT give MTA ANY excuse to not hire you. From the time you take the test, prepare for the job. You'll thank yourself 3 1/2 - 4 years later.
If anyone has anything else to add here, feel free.