Cut numbers for your wrapping paper.
Cut numbers 1-24 from a Stendig calendar (of you have one), making sure to leave enough room around each number to completely wrap each gift or activity note. OR if you only have a few calendar pages to work with, you could always just cut each number without any room around each one and then attach the numbers to wrapping gifts or activity notes separately. Whatever is easiest for you.
Plan each day and wrap presents.
I found it really helpful to plan out the activities and gifts each day quickly before staring to wrap everything. I saved all the family activities for weekends and days I knew we'd all be available and around all day. And smaller activities / gifts around the house (like small craft project days, books, etc) on the weekdays. And any ornaments or the sensitive items (like Christmas books), I tried to put toward the beginning of the month so we'd have more time to enjoy them.
Once everything was planned out, I wrapped each gift, added a little tape, and set them aside for tying string (next step).
Hang the wrapped gifts from a string wherever you'd like.
I hung our advent calendar on a peg rail (from this Etsy shop) that we have in the kitchen already and added some garland and ornaments to make it feel more festive. Already had both on hand from decorating other parts of the house.
I'm all about keeping it simple when it comes to this stuff though. So there's no need to add any extra decoration unless you're feeling extra festive. I'm constantly reminding myself that the magic is in attempting to make it stress-free, otherwise it won't be fun for me or my kid.
You can also hang all of the calendar 'gifts' from a large branch, wood dowel, a doorknob, even a staircase. Pretty much anywhere you can think of.
And that's it! Let me know if you have any questions. But that's how we made our advent calendar. Hope it's helpful for those that want to give it a try.