You will discover free template for invoices in a large range of formats, and some of them may already be there in your computer, such as Microsoft Word, HTML, Microsoft Excel and PDF etc. Many free templates come with time-saving features, such as standard logos, along with other options you may like including in your individual logo - automatic insertion of date of invoicing, built-in calculation system and drop down menus - allowing you to choose various items to modify conveniently the template for your needs.
Writing templates are widely available online. A Google search will lead you to websites that offer downloads of different templates. Some of them are even free. These prepared formats often come in predetermined categories and include sections like the title, introduction, list, and ending paragraph. All you have to do is fill up these sections depending on your chosen content.