One of the coolest things about being abroad is seeing how everyone documents their travels.
There's just so many different ways to journal about your experience. I'm personally a big fan of the old fashioned writing in a diary every day. I like the process of recounting my days and having a physical token of my travels. But you can tailor it to your tastes.
Maybe keep a blog all about your journey. This way you can write down what you're up to and add in all the cool pictures you've taken. Plus its easily shared with friends and family so they can keep up with your adventures too.
For the social media guru, consider creating a travel insta. Its a fun way to share all the cool pics you've taken but you don't have to do a ton of writing if that's not your thing. Annnndd, making a travel insta means you still have your own insta account so you get to post twice the pictures!
One of my friends sends out an email update each week. Again, its a way to document the experience but you can send it out to the people you want to see it. Plus this way people can respond to you which is fun!
Or even something as simple as taking a picture of a door in each town you visit. Whatever you do, make it your own!