Two notes about using Venmo
Venmo is well into the mainstream now, but I still see many people not doing these two things. I highly recommend both.
1. If someone owes you money, send a request.
I have tons of friends that will buy something for everyone and say in a group chat or just casually out loud, "yeah no worries, just Venmo me for it." And everyone promptly forgets or doesn't worry about it.
They are happy to pay you. You just have to make it dead simple for them. Like any lender, if you put up the money, it's on you to go collect. Thankfully, Venmo's request feature solves this problem. Figure out how much each person owes you, and actually send them a request in the app itself. That way, they can pay you simply by clicking "Pay" when they get that notification. Done. No thinking required.
If they don't pay you, Venmo keeps track of when you sent the request and how many days it's been. You can periodically remind them too. As long as it takes for them to cough up what they owe you.
Implement this and watch your pay back rates skyrocket.
2. Set your Payment Privacy to "Private."
This shouldn't need much explanation, but Venmo is set to public by default, meaning everyone else using the app can see who you paid, when you paid them, and the description you wrote.
If you use the app even just a few times, someone could learn a lot about you from that. Don't let it be known to God and everyone who you're with, when you were with them, and what you were buying or paying for. Keep that close to the vest.