When adding a form to your website, make sure to test the tab order with your keyboard. Keyboard-only users won't be able to click to get to the input areas, so it is important that the flow through your form follows a logical order.
The order should be in the way the language is read. For most languages, this means the order should be left to right, top to bottom. If you are offering a form for a language that follows a different order, keep that in mind as well.