ThanksCredit cards? 

@Bob Daniels - I thought a HELOC is closer to a low interest credit card that can be used (partially or fully) paid off and used again.

I've seen several places that offer something like 5% on the first 10k, but there are always additional things you must do in order to get that higher % rate, such as having a certain amount of direct deposit into the account every month, or spending a certain amount on their debit card each month.  

Make sure the attendant wears a fluorescent vest to identify himself.Mount a camera and post a sign that the lot is monitored and protected to deter robberies.also handy to have a swipe device to accept credit cards for payment.

Mainly as they likely do not have cards or  accounts to use for on-line payments.Problem I see is that if I give them the account number, how would I know WHO paid? 

Self Advertising: Business Cards, Social Media Posts, Mailing post card styled ad to renters/people looking to buy, and mailing hand written notes to past clients.Business Cards: Hand out after conversations, put out in local stores/restaurants (after receiving permission) and put in all flyers/ads/notes mailed.Social Media Posts: Put out helpful information and use colorful images/texts to get peoples attention.Mailing Post Card Style Ads: Will advertise that you're willing to help new clients.

First 2 months cash but they would never bring us a receipt so August 2019 we paid off a card, which they did take the funds.

I even gave her a 50$ home depot gift card at closing as a house warming gift .

I just passed my real estate license exam (just yesterday) and am looking into getting a credit card for business expenses.

This is probably a scenario best addressed with some combination of your credit cards, HELOC, private money from folks you've networked with, other stuff like that.