If you're manually creating the invoice using Microsoft Word or Google Drive Templates for invoices, you'll need to include a breakdown of the services rendered and any additional charges associated with your work.
Product or service details: Specify Description, Quantity, Rate, Amount and Subtotal. The more details you include on the invoice, the better. This way, your client will know exactly what they are paying for upon receiving the invoice. Make sure that your client can understand every item, so that as soon as they receive the invoice, they can pay you instead of asking questions and delaying the process.