"Lender" and "Florida" might be so common it will spam your inbox.

I am unsure how to tackle this issue and hoping I can get some advice so I do not end up costing myself more time and money.I have a tenant that has never paid rent on time and is currently behind on payments.

CL has so much spam, and is difficult to search, that it has become less effective for marketing rentals.

The model for the last year has been putting the biggest fires out first and letting the smaller ones lie until I have the time to tackle them.

I do think it's a good learning experience for an investor to tackle at least once because by the nature of being able to be either redeemed out or taking title for whatever exit purposes you are thinking, it's a relatively safe prospect.  

And lastly, if you go that route, ideally try to make $100-$150 cash flow per bedroom in your home after the mortgage (P+I+taxes) -- but if your rents could cover your mortgage, and give you just a small margin of profit. then I would choose the heloc, you go rent somewhere else, and then wait to utilize the capital based on the project you feel comfortable with and want to tackle.  

Which niche I should tackle.

Also a lot of them do not have the work ethic/mindset to tackle this aspect of RE and be successful.

I had so many of them that were spam, and then I had to type up a lengthy email to get credit applied back to my account. 

It is total spam and it is against the law.