It can be tricky to determine what size to order when shopping online, but there are a few things you can keep in mind that will help make the process easier. First, take accurate measurements of your body and compare them to the size chart provided by the retailer. Pay attention to not just overall garment dimensions, but also details like sleeve length and inseam measurements. It can also be helpful to read customer reviews to see if others have found a particular item to run large or small. If you're still unsure about which size to choose, some retailers allow you to order multiple sizes and return the ones that don't fit. And finally, don't hesitate to contact the customer service department of the store you're shopping with if you have any questions - they'll be happy to help!