Paypal is still one of the most convenient and safest payment method out there I have been using it for well over a decade as a buyer and a seller without issues.
You can also use Square which now allows you to send Email invoices https://squareup.com/?pcrid=67780945...reup+com&pmt=e
You can also take credit card with a credit card processor such as
I have all 3, Paypal (with Paypal Here to swipe credit card in person), Square and EMS http://plusbyems.com/ (which I rarely use)
I also accept checks and money orders.
If you want to do business you need to accept the popular and convenient form of payments.