I may be frugal but I still use credit cards. I use them for business and I use them for personal. I have a couple 'rules' for credit cards. I don't use them for anything that hasn't been budgeted for. I also don't use them for things like groceries.
And I reconcile them every month.
How do I do this? Easily?
I have an accordion file where I keep monthly bills. The credit card receipts go into a separate compartment. One compartment per credit card. Then when I receive my statement, I match each line on the credit card statement with the receipt. If all goes well, I staple everything together and happily pay the bill (well, not happily, more like dutifully).
In a perfect world, that is what would happen.
I'm not perfect and neither is the world. So I usually have a few lines unaccounted for. If I'm lucky, I can figure the charge out. I check to ensure that it wasn't billed the previous month (that happens). If that wasn't the case, I write the explanation on the statement and move forward.
If I don't know what the charge is for, I'll call either the credit card company or the vendor listed (if the vendor is clear). Most times, I'll then remember what I purchased. If I still don't know, I'll ask the vendor for a copy of the receipt. If after all that, I still have no clue (and don't recognize my own siggy on the receipt), I'll work with my credit card company to contest it.