Tax laws and payments suck in multiple levels. Simply forget about them with Quaderno. It runs like butter with Stripe so it cannot get better.

Version control is complex so having a) responsive support line both fast in response and comprehensive in their support, is great; but also b) easy to use GUIs reduce complexity: a nifty branch explorer helps you navigate the most convoluted of architectures.

Plastic SCM is a solid, reliable piece of software that will help you with get things done.