The best thing about using an invoice system is that you can track your time against the amount you're getting paid for each task. In order to run a successful business, you want your hourly rate to be profitable so you're not losing time and money. Another benefit of using an invoicing system is that you'll never save over an invoice and lose the work you've calculated for another client.
Terms (or Payment Terms): Invoice terms depend on common practices of your industry, your relationship with the customer, and your cash flow needs. For example, “Net 30” means that the invoice is due 30 days after the Invoice Date. Be mindful some businesses may pay later than the stated due date, so you may want to include a buffer to keep your business free from a cash flow gap.