You may still be mailing paper invoices or you may be doing all your billing and payments over the internet, either using a website that accepts charge cards or an online payment system that uses email like PayPal. As a freelancer, this affects the part of your invoice that lists how you want to get paid. You may even offer your client a variety of payment options, and all of those should be mentioned on your invoice.
If your business ships products to customers, a sales invoice template is the perfect choice. This template allows you to include shipping information, and it calculates the tax along with shipping and handling. This is ideal for small business invoicing, looks professional, and coordinates with the packing slip and purchase order templates.