What invoicing tools should freelancers use for currencies, reminders and terms?

[Joseph.R]

I've been freelancing as a graphic designer for about six months, and my current freelance invoicing system is a mess of scattered emails and manually created PDFs, which is causing delays in getting paid. I need to set up a more professional and automated process. What software or tools do you recommend for creating and tracking invoices, handling international clients with different currencies, and setting up polite but firm payment reminders? I'd also like to know what standard payment terms and late fee policies are considered reasonable in the creative industry.