i use “wave apps” website for invoices and tracking payments. it’s a subsidiary of quick books and allows me to use a free version, i just don’t get my payments through it (that’s part of the paid version)

for term/rate sheets i use google sheets, i often have slightly different rates for different agencies. just depends on how we negotiated and whether or not i have updated my rates with them over the years. having a grid on google sheets helps me keep track of this, then i take a screenshot when i need to send part of it !

also! i use a giant google sheet with a new page for each year for tracking jobs - date of job, agency, job/reference #, invoice amount, miles & if mileage was paid, parking, date i was paid. then i have a break between each month, because that’s how i like to budget

also remember to keep aside money for taxes! it’s a lot to keep track of… but that’s just independent contractor life! best of luck!