I use SmartMove through Bigger Pockets here to do the credit/background checks. You email the link, they click it, fill it out, pay the $35 fee, and the results come to me. I've used it since day 1 and it works great.
I have locked storage closets under the stairs in my 8-plex. I put a drop slot in one of them with a bucket on the other side. They just drop rent, contracts, applications, etc. right in there for me. It works great because it's right outside everyone's door so there's no excuses for it being late. They also have the option of doing ACH through the QuickBooks invoice I email them every month, or just dropping it at the bank. I have one tenant that pays cash, which I don't prefer, but he's old and I don't feel like arguing with him about it. Rent is due on the 1st, but I give a grace period until the 5th. I stop by on the 6th and collect it all, along with the coin out of the washer and dryer.
Hope this helps. Good luck :)