It obviously may not be possible for your specific business but if it is I'd encourage you to try and arrange things so you don't have to invoice people at all.<p>For <a href="http://comfypage.com" rel="nofollow">http://comfypage.com</a> we have a small set of additional services we can provide. We used to invoice people but these days for most stuff people fill out a form and pay online then we get an email that says "person X wants Y done" No invoicing required and we get paid up front so there's no chasing payments involved.<p>We're probably losing a percentage of customers who don't like this process but the amount of time we spend on admin tasks is basically zero.