As a freelancer or small business, one of the biggest decisions you can make (from a business perspective, at least) is how to track your time and invoice your clients. There are a few really good options out there. Quickbooks Online seems to be a good solution, but it can get pretty expensive pretty quickly. A friend of mine recommended CurdBee, which looks like a pretty nice option, too.
My software of choice, though, is an application called Paymo. Paymo works extremely well, is easy to use, feature-rich and is extremely affordable. There are basically only two reasons you would ever pay to use Paymo. The first would be if you need to issue more than 3 invoices in a month. The other reason would be if you need to allow more than 2 users (yourself and one other) to track their time in the application.