I noticed that the previous owner let them pay half the security deposit and the other half later, which is a red flag.

When I started, I  submitted great deals to a corporate cash buyer,  they went behind my back and secure the deals with the sellers, after the  contracts expired.

However, they can deduct the interest they pay to you as part of the seller-financed agreement—if the loan is secured by the property and you provide them with a Form 1098 (Mortgage Interest Statement) for their records.

Ensure you collect a proper security deposit (typically one month's rent in Florida) to cover potential damages.Your plan to increase rent next year makes sense given rising costs (taxes, insurance, and maintenance).

Currently, I don’t have secured funding, and my plan is to explore options like partnering with a partner and seeking assistance from a hard money lender.

Real estate transactions, especially flips, come with specific tax implications such as the potential for dealer classification, short-term capital gains, and cost allocation for renovations, which can significantly impact your tax liability.

Renter's Insurance is a cheap date for the tenant; it protects their security deposit and assets. 

Quote from @Matt Meier: Good morning,I’ve come across a renovation property available at a significant discount and would like to secure it without going the traditional 6-month financing route.

Some lenders offer creative solutions, like a cross-collateralized loan, where they use your existing equity as security without refinancing the duplex.Another idea is partnering with private lenders or exploring a second-position mortgage, depending on your lender's terms.

Separate accounts per property incurs a lot of overhead, such as minimum balances or fees for missing the minimum.I use separate accounts for each tenant's security deposits.