Are you considering how you keep track of your freelance expenses and income? I've found that utilizing a free web app called "Wave Apps" has helped me track expenses such as mileage and allows me to easily invoice.
There is a paid option for the service but for most starting free should be 100% fine.
I've found when it comes time for taxes, being able to shoot off a few pdf's to my tax person makes my life and there life easier.
At the moment I don't use any software or apps to track my income and expenses. When I do need to declare my income and expenses each month I tend to keep track through my PayPal as that is where I receive most if not all payments each month and I write down any expenses through that month to help me keep track.
I am going to look into Wave Apps though, it may help to keep things more organized.
I am an old school person. I use notepad to track my income and expenses. Every time I receive payment for my work, I note it down and everything I spend my income, I note it down. Based on my income and expenses, I make my budget.
Tracking expenses and income is very crucial for freelancers. It's neccesary to have a clear record of your expenses because it makes things so easy for you.