I have always found that an Excel spreadsheet is the cat's meow. The basics go on the sheet when I accept a job: Dates, client, street address, MSP, fee, bonus, reimbursement and any notes (such as time of day, scheduler name, date accepted) that may be useful to you. When I perform the job I note the mileage, the date actually performed, the date reported, the actual reimbursement expected (useful because may be an 'up to $X' and often I don't spend that much). On my sheets there is a total of fee, bonus and reimbursement so that I know what I am expecting. When I am paid I revisit the job again to verify I receive the correct amount and put a payment received date. When the job is paid I highlight the job in blue and when a month's sheet has turned all blue I know I am fully paid up.
The beauty of a spreadsheet is that you can add columns as needed for things you want to keep track of with your jobs. They also can be backed up easily so that you never find you have lost all your data.