I like to mark each milestone with a small at-home celebration. Nothing too extravagant, but something fun and memorable for the whole family!
For example, when our little one took their first steps, we had a "walking party!" We turned on some fun music, brought out some of baby's favorite treats (crushed up into finger food size) and let everyone in the family take those first few steps with baby. It was such a happy moment seeing everyone cheering and celebrating this together.
For bigger milestones like birthdays, I love to go all out with decorations - balloons, streamers, banners, the whole shebang! I also like to prepare some special treats and perhaps organize a few simple games or activities related to the theme of the milestone. Dressing up is a must, with matching outfits for the occasion! It makes it so much fun looking back at the photos later on, and it helps create those lasting memories.
I think these celebrations are also great because they help you reflect on your little one's progress and appreciate all the hard work (theirs and yours!). Well done, momma (or daddy) bear! You're doing a great job!