I log on to my accounts regularly to look at balance and history. I put all passwords into KeePassDX/XC so I can get to my pin if I forget it.

My whole life up to about 8 years ago, I used a checkbook and I was always able to keep it balanced by regularly comparing what I had on my register to what came back in the monthly statement. I was able to track down where I was wrong and put a little check mark next to the verified balance.

I finally gave up this routine because I almost never write checks anymore (like once a year or so), and I'm convinced (after a few decades) that the bank gets it right. I review my spending regularly to keep my expenses as low as possible and avoid getting too profligate.

Paying for everything with cash makes it harder to manage your spending since you have to track it manually. That said, I don't use my debit card for purchases because I am paranoid about privacy on the one hand, and I don't want to be tracking my balances quite that closely. Instead, I withdraw some cash with the expectation that it will last about 2 weeks, use that for day-to-day stuff, and use my rewards credit card for most significant purchases.

I keep track of my card balance loosely to ensure I don't over-spend and pay that in full each month. Unfortunately, it's easy to track my purchasing history on the card if someone somehow gets access, but at least I get cash back to apply when needed.

By alloting myself a certain amount of cash, I don't worry about tracking every cash purchase. I track at a higher level whether I should spend or not, and curtail whim spending based on cash on hand and how long since my last ATM visit. I review my credit card balance for similar reasons - how much can I legitimately pay at the end of the pay period? Keep the balance below that at all costs.