I had a hard time at first, and on larger projects I do tell them payment maid with credit I will add a fee.
It does suck paying out some interest, but when I look at the other money savings, time savings, fuel savings, it's a no brainer.
I literally fell that accepting credit cards saves me 45 mins of time everyday and at least 1 gal of gas, and turns other dead beat customers into paying outstanding invoices.
It sucks buying spare parts too, but you know that $20.00 in random nuts and bolts sitting at your shop, will save you $20.00 the first time you need to open the bin and pull 1 single set out. After that it's just money saved