@Sunny K. welcome to BP, you certainly found an excellent source for guys just starting out(myself included)! To answer your questions to my current knowledge:
(1) Is my location/criteria above too narrow or too broad ?
-I'd say there's nothing wrong with digging deeper and research each of those areas but definitely you'll want to narrow in on a certain county(s) for your first few(my opinon). Think about how much travel you'd like(i.e. a water heater breaks in Texas rental and you need to be on site for an eviction in NC the same time). Maybe once you have a few in one area then snatch up another and start over so you have groupings in some hot areas?
(2) What are some ideal places/zipcodes in the above cities/states that are worth diving into ?
- I have a few for each city that I found interesting, should I create a new post for each city for further discussion?
-I'd really narrow down the criteria you're looking for with cash flow you'd like, budget, vacancy you can afford, repairs your willing to do yourself etc...Personally, I know theres a few areas that are hot now from Montclair NJ to Bloomfield NJ.
(3) What do I need to know before my 1st deal so I won't screw up
-I havent done one yet so I cant speak to loudly about this but I'd just say to know the numbers until you're blue in the face. Make sure you have done your homework on that house and know every piece of information you can in the area and have a good network of people local to bounce things off of. (Feel free to PM if you're interested in meetups in NJ)
I wish you the best of luck and congrats again on taking your first step by posting and taking action. Everyone is very helpful here and dont hesitate to reach out.