First things first: let’s clear up how to even spell duffle bag. Yes, you can spell it duffel or duffle. Both are correct. However, when it comes to how to pack travel duffle bags - there is definitely a right way.
Making a list will help ensure you don’t forget any necessities, and gathering your items first (rather than stuffing them in your duffel bag as you grab them) will help you make the most of the space you have available.
It’s common sense, but if you’re not thinking ahead you will make the mistake of throwing in heavier items on top at the last minute, crushing and wrinkling what’s underneath. Or, you’ll end up having to dig through a layer of low-priority items to access your essentials near the bottom of your duffle.
Roll shirts into a cylindrical shape to save space and prevent extra wrinkling. Then, place items in a row in your duffel bag. Pack smaller and lighter-weight items (like socks) inside shoes and other small remaining spaces.
Things like toiletries, medications, and food can be added to the top of the main duffle bag space, or tucked into zippered pockets if your bag has those.
Still have more to pack? Give your duffle bag a shake to help the contents settle, giving you just a little more space to work with. Still have more to pack? Sorry, man. You need to start over at step 1 - and shorten that list.