[senseitit]

I second Paymo, which is basically designed around client work. You can create multiple projects with different billing methods and track time on them, which can then be pulled into an invoice for a client. This way you have a concrete idea of how you spend your time vs. how much you get paid for it.

The free plan should be enough for planning and tracking project progress. It's limited to 3 invoices though, so you might need to buy a paid plan for advanced accounting features.

https://www.paymoapp.com/