Hi Michelle - Lot's of great points already made here. You can definitely do 90 units on your first deal but will need to partner with someone to borrow their credibility. A deal that size will more than likely come from broker relationships, but again for them to take you seriously you will need to partner with someone who has a track record. You would have to bring value to someone for them to partner with you. You could either focus on raising money for the deal and bring that to the table or finding a deal, but that would be difficult since a deal that size is unlikely to get awarded to someone without a track record. The deal will not just be awarded to who pays the most, but to who is likely to be able to close on it. I would suggest one of 2 paths for you...
1. For a larger deal, find an experienced owner who owns buildings around that unit count and partner with them, your contribution would be raising money. You can find experienced owners at multifamily meet ups/REIA.
2. For a smaller deal, partner with an experienced owner in a unit count of that same range. Your contribution would be to either raise money, or you could find the deal. This is because lower unit count deals like 30 units or so are often owned by mom and pop owners. Due to this, you wont have to necessarily deal with brokers and you can contact the owners directly. You can find owners lists for the area you are looking for free from the county records office or pay for a more refined list through list companies like listsource etc. From there you may need to skip trace them to get a phone number. Then call them/mail them etc.
Lastly I would suggest sticking to 1 area for now because you pretty much need to find an entire team in the area you choose. Property manager, brokers, lenders, etc. Working more than one area will just make it much more difficult. Of the areas you mentioned, I think they are good because cap rates in those areas are high, Fort Lauderdale's job growth is on the low side though, so you may want to take that into consideration. That is for the metro area as a whole though and as you know real estate is always very local.
Best,
juan